Observations, 
Recommendations, 
and Technical Guidance 
FFEEMA 333399 // Maarrcchh 11999999 
IMAGE COURTESY NASA Federal Emergency Management Agency 
Mitigation Directorate 
Washington, DC, 
Region II, New York, NY 
and the Caribbean Area Office 
Federal Emergency Management Agency 
Mitigation Directorate 
Washington, DC, 
Region II, New York, NY 
and the Caribbean Area Office 
Building Performance Assessment Report
The Building Performance Assessment Process 
In response to hurricanes, floods, earthquakes, and other 
disasters, the Federal Emergency Management Agency (FEMA) 
often deploys Building Performance Assessment Teams (BPATs) to 
conduct field investigations at disaster sites. The members of a 
BPAT include representatives of public and private sector entities 
who are experts in specific technical fields such as structural and 
civil engineering, building design and construction, and building 
code development and enforcement. BPATs inspect disasterinduced 
damages incurred by residential and commercial buildings 
and other manmade structures; evaluate local design practices, 
construction methods and materials, building codes, and 
building inspection and code enforcement processes; and make 
recommendations regarding design, construction, and code 
issues. With the goal of reducing the damage caused by future 
disasters, the BPAT process is an important part of FEMA.s hazard 
mitigation activities. For more information about the BPAT program 
or if you are interested in becoming a member, please visit 
our website at www.fema.gov/mit/bpat.
Throughout Puerto Rico, the BPAT visited communities 
where people had lost their life.s belongings and literally did 
not have a roof over their heads. The team was struck by the 
dignity of those individuals who had suffered great losses and 
appreciated the courtesy and hospitality that was extended to 
them. The team also appreciated their patience with the BPAT.s 
questions. This report is dedicated to these individuals, their 
families, and their friends. Their remarkable spirit is summarized 
by the saying .al mal tiempo, buena cara., which translates as 
.hard times, strong faces..
Observations, 
Recommendations, 
and Technical Guidance 
FEMA 339 / March 1999 
Federal Emergency Management Agency 
Mitigation Directorate 
Washington, DC, 
Region II, New York, NY 
and the Caribbean Area Office 
In Puerto Rico 
Hurricane Georges 
PUERTO RICO 
Building Performance Assessment Report
Building Performance Assessment: Hurricane Georges In Puerto Rico i 
TABLE OF CONTENTS 
Table of Contents 
List of Acronyms ...................................................................................................... ix 
1 Executive Summary............................................................................................... 1-1 
2 Introduction .......................................................................................................... 2-1 
2.1 Background of Storm ............................................................................................ 2-1 
2.2 Team Composition................................................................................................. 2-3 
2.3 Methodology .......................................................................................................... 2-4 
2.4 Planning Regulations ............................................................................................. 2-4 
2.5 Floodplain Management Regulations .................................................................... 2-7 
2.6 Puerto Rico Seismicity ............................................................................................ 2-7 
3 Assessment and Characterization of Damages ..................................................... 3-1 
3.1 Wind Effects ........................................................................................................... 3-1 
3.2 Riverine and Coastal Flooding ............................................................................... 3-2 
3.3 Landslides .............................................................................................................. 3-8 
3.4 Overview of Buildings Evaluated ......................................................................... 3-10 
3.4.1 Concrete/Masonry Structures with Concrete Roof Decks ....................... 3-10 
3.4.2 Concrete/Masonry Structures with Wood-Frame Roof Structures ........... 3-12 
3.4.3 Combination Structures, Concrete/Masonry and Wood-Frame 
Structures ................................................................................................ 3-13 
3.4.4 All Wood-Frame Structures ...................................................................... 3-15 
4 Structural Performance......................................................................................... 4-1 
4.1 Reinforced Concrete .............................................................................................. 4-4 
4.1.1 Reinforced Concrete Mid- and High-Rise Buildings .................................. 4-4 
4.1.2 Reinforced Concrete Essential Facilities .................................................... 4-5 
4.1.3 Concrete/Masonry Structures with Concrete Roof Decks ......................... 4-5 
4.2 Masonry .................................................................................................................. 4-6 
4.2.1 Masonry Commercial Buildings ................................................................. 4-6 
4.2.2 Residential Concrete/Masonry Structures with Wood-Frame 
Roof Structures .......................................................................................... 4-9 
4.3 Wood-Frame Buildings ......................................................................................... 4-10 
4.3.1 Commercial Wood-Frame Buildings ........................................................ 4-10 
4.3.2 Residential Wood-Frame Buildings .......................................................... 4-10 
4.3.2.1 Residential Wood-Frame Walls ....................................................... 4-11 
4.3.2.2 Residential Wood-Frame Roof Structures ...................................... 4-13 
4.3.2.3 Residential Wood-Frame Floor Systems and 
Foundation Connections ............................................................... 4-14
ii Building Performance Assessment: Hurricane Georges In Puerto Rico 
TABLE OF CONTENTS 
4.4 Hold-Down Cables ............................................................................................... 4-16 
4.5 Structural Seismic Considerations ....................................................................... 4-17 
5 Building Envelope Performance ............................................................................ 5-1 
5.1 Doors ..................................................................................................................... 5-1 
5.1.1 Glass Doors ................................................................................................ 5-1 
5.1.2 Personnel Doors ........................................................................................ 5-3 
5.1.3 Security Grilles, Rolling (Overhead) and Garage Doors ............................ 5-4 
5.2 Non-Load Bearing Walls, Wall Coverings, and Soffits ............................................. 5-5 
5.2.1 Non-Load Bearing Walls and Soffits ........................................................... 5-6 
5.2.2 Wall Coverings ............................................................................................ 5-8 
5.3 Roof Coverings ..................................................................................................... 5-11 
5.3.1 Metal Panels ............................................................................................. 5-11 
5.3.2 Exposed Concrete and Liquid-Applied Membranes 
Over Concrete ......................................................................................... 5-14 
5.3.3 Tile ........................................................................................................... 5-15 
5.3.4 Liquid-Applied Membranes Over Plywood .............................................. 5-16 
5.3.5 Built-Up Membranes ................................................................................ 5-16 
5.3.6 Sprayed Polyurethane Foam.................................................................... 5-18 
5.3.7 Other Roof Coverings .............................................................................. 5-18 
5.4 Windows, Shutters, and Skylights ........................................................................ 5-18 
5.4.1 Windows .................................................................................................. 5-19 
5.4.2 Shutters .................................................................................................... 5-23 
5.4.3 Skylights ................................................................................................... 5-28 
5.5 Seismic Resistance of Nonstructural Elements .................................................... 5-28 
6 Exterior Mechanical and Electrical Equipment .................................................... 6-1 
7 Electrical Distribution System ............................................................................. 7-1 
8 Conclusions ........................................................................................................... 8-1 
8.1 General Conclusions .............................................................................................. 8-1 
8.1.1 Mitigation Efforts ........................................................................................ 8-2 
8.1.2 Wind Mitigation for Existing Buildings ...................................................... 8-4 
8.2 Planning Regulations in Puerto Rico .................................................................... 8-4 
8.2.1 Wind Provisions of Planning Regulation 7 ................................................. 8-5 
8.2.2 Seismic Provisions of Planning Regulation 7 .............................................. 8-5 
8.2.3 Floodplain Management Provisions of Planning Regulation 13 ................. 8-6 
8.3 Regulatory Administration and Enforcement ........................................................ 8-6 
8.4 Training and Continuing Education ...................................................................... 8-7 
8.4.1 Government of Puerto Rico Personnel ...................................................... 8-7 
8.4.2 Design Professionals and Building Contractors ......................................... 8-7 
8.5 Structural ............................................................................................................... 8-7 
8.5.1 Structural Seismic Conclusions .................................................................. 8-8 
8.6 Architectural .......................................................................................................... 8-8 
8.6.1 Doors ......................................................................................................... 8-9 
8.6.2 Walls ........................................................................................................... 8-9 
8.6.3 Roof Coverings ........................................................................................... 8-9 
8.6.4 Glazing ....................................................................................................... 8-9 
8.6.5 Shutter Systems and Impact-Resistant Glazing ........................................ 8-10 
8.6.6 Weatherstripping ..................................................................................... 8-10
Building Performance Assessment: Hurricane Georges In Puerto Rico iii 
TABLE OF CONTENTS 
8.6.7 Seismic Resistance of Nonstructural Elements ........................................ 8-10 
8.7 Exterior Mechanical and Electrical Equipment .................................................... 8-10 
9 Recommendations ................................................................................................. 9-1 
9.1 General Recommendations ................................................................................... 9-1 
9.2 Training and Continuing Education ...................................................................... 9-2 
9.2.1 Government of Puerto Rico Personnel ...................................................... 9-2 
9.2.2 Design Professionals and Building Contractors ......................................... 9-2 
9.3 Codes and Regulations .......................................................................................... 9-3 
9.3.1 Planning Regulation 7 ................................................................................ 9-3 
9.3.2 Floodplain Management Provisions of Planning Regulation 13 ................. 9-4 
9.3.3 Evaluation, Submittals, and Product Approval ........................................... 9-5 
9.4 Essential Facilities ................................................................................................... 9-5 
9.5 Residential Buildings ............................................................................................. 9-5 
9.6 Structural and Architectural Performance ............................................................. 9-5 
9.7 Electric Power Distribution .................................................................................... 9-6 
10 References ........................................................................................................... 10-1 
Appendix A: Members of the Building Performance Assessment Team for 
Hurricane Georges 
Appendix B: Presidential Disaster Declarations In Puerto Rico 
Acknowledgments
iv Building Performance Assessment: Hurricane Georges In Puerto Rico 
TABLE OF CONTENTS 
List of Figures and Tables 
Figure 2-1 History of hurricanes in Puerto Rico. ............................................................. 2-2 
Table 2-1 The Saffir-Simpson Scale ................................................................................ 2-3 
Figure 2-2 Flyover routes from October 2 and October 3. ............................................. 2-5 
Figure 2-3 Locations of ground investigation by the BPAT. ............................................. 2-6 
Figure 3-1 The abrupt change of topography in this community outside Loiza 
caused a speedup in the wind that flows over and around the 
buildings located on the hill beyond. ............................................................ 3-2 
Figure 3-2 Wind damage from Hurricane Georges to residential 
buildings in Puerto Rico. ................................................................................ 3-2 
Figure 3-3 Typical non-elevated structures in a community located 
entirely in an SFHA. ....................................................................................... 3-3 
Figure 3-4 This flood gate located in Adjuntas prevented backwater from 
flooding homes located behind it. ................................................................. 3-3 
Figure 3-5 Residential area on the opposite side of the river from the 
floodwall in Figure 3-4. .................................................................................. 3-4 
Figure 3-6 Floodwaters eroded soil and undermined the foundation 
system of this building. .................................................................................. 3-4 
Figure 3-7 Riverbank erosion resulted in the undermining of the building 
foundations of a school and house in Jayuya. ................................................ 3-5 
Figure 3-8 Typical construction adjacent to and over the river. ...................................... 3-5 
Figure 3-9 Structure along the coast damaged by storm surge 
and wave action. ............................................................................................ 3-6 
Figure 3-10 Proper elevation construction techniques for construction 
in A-Zones. ..................................................................................................... 3-6 
Figure 3-11 Comparison of building foundation and elevation requirements 
in V-Zones and A-Zones. ................................................................................ 3-7 
Figure 3-12 Bridge outside Adjuntas collapsed due to insufficient design to 
resist the effects of floodwaters. ..................................................................... 3-7 
Figure 3-13 Severely damaged water treatment facility located 
in the floodplain in Jayuya. ............................................................................ 3-8 
Figure 3-14 Aerial view of a now uninhabitable house caught in 
a landslide. ..................................................................................................... 3-8 
Figure 3-15 A landslide inundated this house with up to 5 feet of soil. ............................ 3-9 
Figure 3-16 Development adjacent to a representative unprotected cut; 
the potential for future landslide activity exists. ............................................ 3-9 
Figure 3-17 Commercial concrete structures with no structural damage. ..................... 3-10 
Figure 3-18 Commercial concrete structure with interior damage observed 
due to breach of building envelope. ............................................................ 3-11 
Figure 3-19 Residential concrete structure in the mountains north of Adjuntas 
with no structural damage following Hurricane Georges. .......................... 3-12 
Figure 3-20 Aerial view of a residential concrete/masonry structure 
with a wood-frame roof structure. ............................................................... 3-13 
Figure 3-21 A combination residential concrete/masonry structure with an 
elevated second-floor concrete slab and a wood-framed upper level. ........ 3-14 
Figure 3-22 A residential concrete/masonry structure under construction. ................... 3-14 
Figure 3-23 A residential wood structure located on the hilltops west of 
Ponce destroyed by wind. ............................................................................ 3-15
Building Performance Assessment: Hurricane Georges In Puerto Rico v 
TABLE OF CONTENTS 
Figure 4-1 Illustration of continuous load path for a wood-frame building. ................... 4-2 
Figure 4-2 A residential community constructed of concrete and masonry 
buildings with concrete roof structures. ........................................................ 4-3 
Figure 4-3 A residential community constructed of wood-frame 
structures only. ............................................................................................... 4-3 
Figure 4-4 Concrete residential structure with foundation damage caused 
by a landslide. ................................................................................................. 4-4 
Figure 4-5 Fire station in Adjuntas. ................................................................................. 4-5 
Figure 4-6 Residential home constructed of reinforced concrete and 
masonry with a reinforced concrete roof deck in the mountains 
outside Adjuntas. ........................................................................................... 4-6 
Figure 4-7 Typical roof system failure between wooden roof system 
and concrete or masonry wall system. ........................................................... 4-7 
Figure 4-8 Termite-damaged wood purlin attached to metal roof panel. ....................... 4-7 
Figure 4-9 Masonry church that lost roof purlins and its corrugated 
metal roof. ...................................................................................................... 4-8 
Figure 4-10 Nailed roof structure from church in Figure 4-9. ........................................... 4-8 
Figure 4-11 Typical nail withdrawal failure in a wood-frame structure 
supported by a masonry wall with little uplift capacity at 
the connection. .............................................................................................. 4-9 
Figure 4-12 Hurricane clips installed in a wood-frame house on Culebra. ..................... 4-10 
Figure 4-13 Example of the failure of wood member in joist hanger 
due to use of improper nails. ....................................................................... 4-11 
Figure 4-14 Example of wood-frame wall construction that failed 
during Hurricane Georges. ......................................................................... 4-12 
Figure 4-15 Wood wall column that failed at connection to sill plate. ............................ 4-12 
Figure 4-16 Typical wooden roof structure with metal roof panels above...................... 4-13 
Figure 4-17 Example of a self-built, wooden roof truss................................................... 4-14 
Figure 4-18 Example of a non-engineered connection between the 
building foundation and the floor system. ................................................... 4-14 
Figure 4-19 Example of an engineered connection between the floor beam 
and a concrete column. ............................................................................... 4-15 
Figure 4-20 Example of a successful wood connection between support 
beam and floor joists. ................................................................................... 4-15 
Figure 4-21 Wood-frame house with metal roof covering with hold-down 
cables that run parallel and perpendicular to the roof ridge line. ............... 4-16 
Figure 4-22 Residential building supported atop tall, unbraced columns. ..................... 4-17 
Figure 4-23 Footing for tall columns shown in Figure 4-22. ........................................... 4-18 
Figure 5-1 Damaged sliding glass door and window assembly in 
a hotel room. ................................................................................................. 5-2 
Figure 5-2 Missiles broke this wood/glass door and several adjacent 
window panes. ............................................................................................... 5-2 
Figure 5-3 A missile traveling right to left struck the window louvers. ........................... 5-3 
Figure 5-4 The security grille on this fire station offers greater wind 
performance reliability than a solid door. ...................................................... 5-4 
Figure 5-5 The gypsum wallboard was blown off of this interior partition 
after the exterior non-load bearing wall was blown away. .............................. 5-5 
Figure 5-6 Rain entered this hospital on Culebra after a water tank struck the 
metal wall panels. ........................................................................................... 5-6
vi Building Performance Assessment: Hurricane Georges In Puerto Rico 
TABLE OF CONTENTS 
Figure 5-7 Failure of an EIFS wall system. ....................................................................... 5-7 
Figure 5-8 Several composite panels blew off from the fascia and 
soffit of this building at the airport on Isla Grande. ....................................... 5-7 
Figure 5-9 The stucco was blown off the corner area of this wall 
where the suction pressures were high. ........................................................ 5-8 
Figure 5-10 House currently under construction. ............................................................ 5-9 
Figure 5-11 In this EIFS covering, the synthetic stucco appeared to be 
well-adhered to the outer EPS layer, but there was minimal 
bonding between the two EPS layers. .......................................................... 5-10 
Figure 5-12 A mortar skim coat was applied over the concrete of this 
building and the ceramic tiles were set in to the mortar. ............................ 5-10 
Figure 5-13 This house was located on a mountain top that experienced 
very high wind conditions. .......................................................................... 5-11 
Figure 5-14 The nail attaching this corrugated metal panel partially 
backed-out. .................................................................................................. 5-12 
Figure 5-15 Only a single row of fasteners were installed along the 
eave and each side of the ridge. ................................................................... 5-12 
Figure 5-16 The metal panels along this rake were insufficiently fastened. .................... 5-13 
Figure 5-17 At this house, a framing member was run up the rake, which 
allowed the metal purlins to be fastened between the nailers (purlins). .... 5-13 
Figure 5-18 Corrugated metal panel wrapped around a power pole. ............................ 5-14 
Figure 5-19 This concrete roof deck did not have a roof covering. ................................ 5-15 
Figure 5-20 These tiles were heavily damaged, although the wind speed 
at this location was not very high. ................................................................ 5-15 
Figure 5-21 This house had a liquid-applied membrane over plywood 
roof sheathing. ............................................................................................. 5-16 
Figure 5-22 This built-up membrane had a mineral surface cap sheet............................ 5-17 
Figure 5-23 The windows in this building were broken by aggregate from 
the built-up roof of a nearby building. ......................................................... 5-17 
Figure 5-24 When these tempered panes broke, they did not produce shards 
of glass, as did the annealed panes. ............................................................. 5-19 
Figure 5-25 Although some annealed panes broke into shards, others 
just broke at the impact point. ..................................................................... 5-19 
Figure 5-26 Half of the window frame on this building was blown out. ......................... 5-20 
Figure 5-27 One pane in the window was broken by a missile, 
perhaps from the palm in the foreground. .................................................. 5-20 
Figure 5-28 This large window was broken by a missile, most likely 
a tree limb. ................................................................................................... 5-21 
Figure 5-29 The glass and frames were blown out at the center room 
on the top floor. ........................................................................................... 5-21 
Figure 5-30 Several window and glass door openings broke during 
the hurricane. .............................................................................................. 5-22 
Figure 5-31 High-energy missiles from a nearby building damaged 
several railings of this building. .................................................................... 5-22 
Figure 5-32 The broken light in the center is laminated. ................................................ 5-23 
Figure 5-33 A combination of boards and metal panel was used to 
construct this shutter. .................................................................................. 5-24 
Figure 5-34 These windows were equipped with permanent head and 
sill shutter tracks, which were attached to the wall with 
closely-spaced fasteners. .............................................................................. 5-24
Building Performance Assessment: Hurricane Georges In Puerto Rico vii 
TABLE OF CONTENTS 
Figure 5-35 Close-up of Figure 5-34. ............................................................................... 5-25 
Figure 5-36 Looking up at a shutter panel held in place by clips. ................................... 5-25 
Figure 5-37 These windows were equipped with roll-up shutters. ................................ 5-26 
Figure 5-38 This house had hinged plywood shutters. .................................................. 5-26 
Figure 5-39 Steel shutters were used on this mid-rise building, which 
had a narrow balcony in front of the windows. ........................................... 5-27 
Figure 5-40 The window lying on the ground was protected by a shutter. .................... 5-27 
Figure 5-41 Lack of seismic resistance of ceiling lights and ducts. .................................. 5-28 
Figure 5-42 Inadequately reinforced CMU partition in house under construction. ....... 5-29 
Figure 6-1 This exhaust fan lost its cowling. .................................................................... 6-1 
Figure 6-2 Most of the solar hot water heaters on this roof 
successfully weathered Hurricane Georges. .................................................. 6-2 
Figure 6-3 Floodwater entered this generator room and reached a 
height of about 2 feet. .................................................................................... 6-2 
Figure 6-4 This service mast is mounted on a concrete pylon........................................ 6-3 
Figure 7-1 Damaged wood pole. ..................................................................................... 7-2 
Figure 7-2 Leaning wood pole due to inadequate pile embedment. ............................. 7-2 
Figure 7-3 Observed crack in concrete pole that appears to be a quality 
control problem. ............................................................................................ 7-3 
Figure 7-4 New wood pole replaced after the hurricane. ............................................... 7-3 
Figure 8-1 Comparison of undamaged concrete/masonry buildings 
with damaged wood-frame building. ............................................................. 8-2 
Figure 8-2 Wood-frame house nearly totally destroyed. ................................................. 8-3 
Figure 8-3 Example of successful mitigation of wood-frame house. ............................... 8-3 
Figure 9-1 Successes and failures in residential buildings after 
Hurricane Georges. ....................................................................................... 9-2 
Table 9-1 Probability of experiencing different events during specified 
yearly periods. ................................................................................................ 9-6
Building Performance Assessment: Hurricane Georges In Puerto Rico ix 
LIST OF ACRONYMS 
List of Acronyms 
A-Zone Special Flood Hazard Areas, excluding V-Zones 
ACI American Concrete Institute 
AISC American Institute of Steel Construction 
ARPE Administración de Reglamentos y Permisos (Regulations and Permits 
Administration) 
ASCE 7-95 American Society of Civil Engineers Standard 7-95 
Minimum Design Loads for Buildings and Other Structures 
ASD Allowable Stress Design 
ASOS Automatic Surface Observing System 
ASTM American Society for Testing and Materials 
BFE Base Flood Elevation 
BOCA Building Officials and Code Administrators 
BPAT Building Performance Assessment Team 
CAV Community Assessment Visit 
CIAPR Colegio de Ingenerios y Agrimensores (College of Engineers and Surveyors) 
CMU Concrete Masonry Unit 
EIFS Exterior Insulating Finishing System 
EO12699 Executive Order 12699 
EO11988 Executive Order 11988 
EPS Expanded Polystyrene System 
FEMA Federal Emergency Management Agency 
FIRM Flood Insurance Rate Map 
HVAC Heating, Ventilation, and Air Conditioning 
IBC International Building Code 
ICBO International Conference of Building Officials 
in inch 
LRFD Load and Resistance Factor Design 
mb millibars 
mph miles per hour 
NEHRP National Earthquake Hazards Reduction Program
x Building Performance Assessment: Hurricane Georges In Puerto Rico 
LIST OF ACRONYMS 
NFIP National Flood Insurance Program 
NOAA National Oceanic and Atmospheric Administration 
NWS National Weather Service 
psf pounds per square foot 
SBC Standard Building Code 
SBCCI Southern Building Code Congress International 
SFHA Special Flood Hazard Area 
UBC Uniform Building Code 
V-Zone An area of special flood hazard extending from offshore to the inland limit of 
a primary frontal dune along an open coast and any other area subject to high 
velocity wave action from storms or seismic sources
Building Performance Assessment: Hurricane Georges In Puerto Rico 1-1 
Section 1 EXECUTIVE SUMMARY 
1 Executive Summary 
On the evening of September 21, 1998, Hurricane Georges made landfall on Puerto 
Rico.s east coast as a strong Category 2 hurricane. It traveled directly over the interior of the 
island, mainly in an east-west direction, and passed off Puerto Rico.s west coast on September 
22. Puerto Rico had not experienced a hurricane of this magnitude since Hurricane Hugo, a 
devastating Category 3 hurricane that passed over the northeast corner of Puerto Rico in a 
southeast to northwest direction in September 1989. 
On September 30, the Federal Emergency Management Agency.s (FEMA) Mitigation 
Directorate deployed a Building Performance Assessment Team (BPAT) to Puerto Rico to 
assess damages caused by Hurricane Georges. The team included architects, engineers, 
planners, insurance specialists, and floodplain management specialists. The BPAT.s mission 
was to assess the performance of buildings and other structures throughout Puerto Rico and 
make recommendations for improving building performance in future events. 
After an aerial assessment of the island, the BPAT conducted field investigations in 
selected areas affected by the storm. The field investigations of significantly damaged areas 
centered on the performance of single-family residential home construction. Isolated 
examples of success and failure in commercial buildings (primarily building envelope issues 
in high-rise buildings) and several essential facilities observed during field investigations were 
also documented. Commercial buildings were not investigated for compliance with current 
structural seismic guidelines. One- and two-family residential buildings, however, were 
investigated for their ability to sustain a seismic event. Seismic resistance of nonstructural 
elements was also observed. 
It is important to note that wind speeds experienced on the island were not of the 
strength to test the design of Puerto Rico.s buildings. A more significant wind event striking 
Puerto Rico would likely have resulted in even more failures than were observed. 
A large number of residential buildings in Puerto Rico experienced structural damage 
from the high winds of Hurricane Georges. This can be attributed to a lack of a continuous 
load path from the roof structure to the foundation that the BPAT observed in most of the 
damaged buildings. In addition, a large number of residential buildings in identified Special 
Flood Hazard Areas (SFHAs) were damaged from floodwaters. 
A limited number of mid- and high-rise buildings were inspected by the BPAT. Damage 
observed at these buildings was to nonstructural elements, including damage to glazing, 
curtain walls, interior walls, and damages to finishes from windborne rain. Building envelope 
damage resulted from loads on the components and windborne debris that broke glazing. 
The BPAT concluded that while not all of the damage caused by Hurricane Georges could 
have been prevented, a significant amount could have been avoided if more buildings had 
been constructed to Puerto Rico.s existing Planning Regulation 7 (building code).
1-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
EXECUTIVE SUMMARY Section 1 
Furthermore, a lack of compliance with and enforcement of Planning Regulation 13 
(floodplain management) contributed to the damages. Additional damage could have been 
avoided if more buildings had been designed and constructed to current codes and 
regulations that address flood, wind, and seismic loads. Although the BPAT observed several 
examples of successful mitigation implementation, many buildings unfortunately received 
too little attention to mitigation. If effective mitigation efforts had been implemented more 
extensively in the design and construction of buildings, the widespread devastation of the 
hurricane would have been substantially reduced. 
Puerto Rico.s Regulations and Permitting Administration (Administración de Regalmentos 
y Permisos [ARPE]) has taken several important steps following Hurricane Georges to 
increase public safety and reduce property damage from natural hazards. These 
steps include: 
n At ARPE.s request, the International Conference of Building Officials (ICBO) 
conducted and completed a peer review of ARPE in January 1999. This peer 
review evaluated the new needs created by Hurricane Georges as well as the reengineering 
effort currently underway. 
n The Government of Puerto Rico, including ARPE, passed emergency regulation in 
December 1998 that repealed Planning Regulation 7 and adopted the 1997 
Uniform Building Code (UBC) as the building code for Puerto Rico. 
n ARPE is positioned to make recommendations concerning building regulations to 
the new Certification and Building Board of Puerto Rico that is expected to be 
created in March 1999 under proposed legislation submitted by the Governor to 
the Puerto Rico Legislature. 
n ARPE and FEMA are implementing a strategic plan to provide the necessary 
training to make the transition to these new building regulations. 
The ICBO.s peer review of ARPE assessed how ARPE administers and enforces planning 
regulations related to building design and construction. The review evaluated ARPE.s current 
needs.and identified unmet needs.to respond effectively to the massive amount of 
reconstruction necessary following Hurricane Georges as well as future construction. The 
peer review resulted in recommendations in the areas of policies, procedures, practices, 
training and education, facilities, salaries, benefits, promotion, and office automation. Since 
the completion of the peer review, FEMA, ICBO, and ARPE have been working closely 
together to develop a plan that meets the identified unmet needs. 
In addition to the recommendations outlined above, the BPAT recommends the 
following: 
n The Government of Puerto Rico should continue supporting positive mitigation 
education efforts undertaken by the Puerto Rico Civil Defense, Colegio de 
Ingenieros y Agrimensores (CIAPR), Colegio de Arquitectos, and the University of 
Puerto Rico College of Engineering in Mayagüez. 
n ARPE and the Puerto Rico Planning Board should use information gathered by the 
Community Assistance Visit (CAV) in May 1998 and from the damage of Hurricane 
Georges to continue to educate homeowners on the risks involved in building in 
floodprone areas. A renewed effort in enforcement of Planning Regulation 13 
during the rebuilding stages, specifically in the permitting process, should result 
in a significant reduction in property loss from future hurricane events. 
n The BPAT agrees with the Government of Puerto Rico.s decision to adopt the 
1997 UBC as an interim step toward adopting the International Building Code
Building Performance Assessment: Hurricane Georges In Puerto Rico 1-3 
Section 1 EXECUTIVE SUMMARY 
(IBC) when it becomes available. Furthermore, the BPAT recommends several 
local amendments be adopted. 
n Essential facilities should be evaluated for their vulnerability to natural hazard 
events. 
n The Government of Puerto Rico should perform a study on its electrical power 
distribution system.
Building Performance Assessment: Hurricane Georges In Puerto Rico 2-1 
Section 2 INTRODUCTION 
2 Introduction 
This report presents FEMA.s Building Performance Assessment Team.s (BPAT) 
observations on the success and failure of buildings in Puerto Rico to withstand the wind and 
flood forces generated by Hurricane Georges. In addition, the seismic resistance of some of 
the buildings observed was assessed. In this report, .buildings. refer to single- and multifamily 
homes, residential buildings, and commercial and industrial buildings. 
Recommendations to improve building performance in future natural disasters in Puerto 
Rico are included. During this building performance assessment, additional consideration 
was given to mitigation success stories, particularly when mitigation successfully reduced 
damages. In the context of this document, mitigation is defined as actions taken to prevent 
building damage and/or minimize the extent and impact of building damage if it occurs. 
A separate team has prepared a BPAT report on the effects of Hurricane Georges in the 
Gulf Coast of the United States. A copy of the Gulf Coast BPAT report is available from FEMA 
by contacting FEMA.s Publication Distribution Center at (800) 480-2520, and requesting FEMA 
Publication #338, or it may be downloaded from the World Wide Web at www.fema.gov. 
2.1 Background of Storm 
Historical data indicate that the island of Puerto Rico has been struck or otherwise 
affected by 10 hurricanes since 1893 [Defensa Civil Estatal de Puerto Rico and FEMA 1996]. 
Their intense rain and devastating wind speeds have caused extensive damage to the island. 
Figure 2-1 shows the path of these hurricanes. Hurricane category designators in Figure 2-1 
(e.g., CAT 2) are based on the Saffir-Simpson scale.1 Central pressure of the hurricane 
(measured in millibars) and wind speed (measured in mph as 1-minute sustained) ranges for 
hurricane categories of the Saffir-Simpson scale are shown in Table 2-1. 
Hurricane Georges formed 400 miles south-southwest of the Cape Verde Islands and 
moved across the Atlantic into the Caribbean on September 16, 1998. It made landfalls in the 
West Indies; Virgin Islands; Puerto Rico; Hispanola, Cuba; the Florida Keys, the Chandeleur 
Islands of Louisiana, and coastal Mississippi. Hurricane Georges was upgraded September 17 
to a Category 4 hurricane as it moved west through the Caribbean packing 150-mph winds 
over open water. The storm was downgraded to a Category 2 once it moved through the 
Leeward, U.S. and British Virgin Islands on September 21. The storm was categorized as a 
tropical storm late afternoon on September 28. Wind speeds are further discussed in 
Section 3.1. 
1 The Saffir-Simpson hurricane scale ranks hurricanes by categories (CAT). These categories are based on the 
central pressure of the hurricane and wind speed (measured as 1-minute sustained).
2-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
INTRODUCTION Section 2 
FIGURE 2-1 History of hurricanes in Puerto Rico. 
Source: Huracanes en Puerto Rico: Guía de Mitigación de Danõs.
Building Performance Assessment: Hurricane Georges In Puerto Rico 2-3 
Section 2 INTRODUCTION 
On the evening of September 21, 1998 Hurricane Georges made landfall on Puerto Rico.s 
east coast as a strong Category 2 hurricane. The storm passed off the west coast of the island 
September 22, most probably as a weak Category 2 hurricane. It traveled directly over the 
island, mainly in an east-west direction. Puerto Rico had not experienced a hurricane of this 
magnitude since Hurricane Hugo, a devastating Category 3 hurricane that passed over the 
northeast corner of Puerto Rico in a southeast to northwest direction in September 1989. 
The only Category 4 and 5 hurricanes to strike the island this century were San Ciprían 
(Category 4, September 1932) and San Felipe (Category 5, September 1928). Prior to 
Hurricane Georges, the last hurricane to hit Puerto Rico was Hortense, which was a Category 
1 hurricane when it passed over the southwest corner of the island in September 1996. 
Rainfall from Hurricane Georges exceeded 18 inches at the center of Puerto Rico at 
Jayuya. The highest recorded level was east of Jayuya at Comerío, which received almost 26 
inches of rain during the two-day period of the storm. Three deaths were directly attributed 
to Hurricane Georges in Puerto Rico and nine others occurred from medical complications 
[National Oceanic and Atmospheric Administration (NOAA) 1998]. 
Hurricane Georges caused extensive damage in Puerto Rico. It was the costliest disaster 
ever for the American Red Cross, which has spent $104 million for recovery in the Caribbean 
and United States combined [New York Times 1998]. Approximately 80 percent of Puerto 
Rico.s 3.8 million people were without power and water at some point during the storm. 
Over 30,000 homes were destroyed and 50,000 more experienced major or minor damage. 
Hurricane Georges destroyed 75 percent of the country.s coffee crop, 95 percent of Puerto 
Rico.s plantains, and 65 percent of its chickens [NOAA 1998]. 
2.2 Team Composition 
On September 30, the FEMA Mitigation Directorate deployed the BPAT to Puerto Rico to 
assess damages caused by Hurricane Georges. The team included architects, engineers, 
planners, floodplain management specialists, and insurance specialists. See Appendix A. 
The BPAT.s mission was to assess the performance of buildings throughout Puerto Rico 
and make recommendations for improving building performance in future events. The BPAT 
process is intended to provide the government of Puerto Rico, local governments, and other 
interested parties guidance for post-hurricane reconstruction with the goal of enhancing the 
performance of buildings exposed to future natural hazards. 
TABLE 2-1 Pressure and wind ranges for hurricane categories of the Saffir-Simpson Scale.
2-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
INTRODUCTION Section 2 
Aerial and ground site investigations were conducted to observe building conditions in 
selected areas affected by the storm. The mission did not include recording the number of 
buildings damaged by Hurricane Georges, determining the frequency of specific types of 
damage, or collecting data that could serve as the basis of statistical analysis. Collectively, the 
team has invested more than 1,000 hours to date conducting site investigations, inspecting 
damages, and preparing documentation. Documentation included field notes and 
photographs. 
Field investigations of significantly damaged areas mainly focused on one- to two-story 
buildings (homes). However, some essential facilities and high-rise commercial and industrial 
buildings were also assessed and are included in this report. 
2.3 Methodology 
The BPAT conducted two aerial assessments of Puerto Rico. The first passed through 
Canóvanas, Humacao, Caguas, Jayuya, Adjuntas, Utuado, Aguadilla, Rincón, Mayagüez, Cabo 
Rojo, Ponce, and Toa Baja. A second flyover of east Puerto Rico included Fajardo and the two 
islands to the east: Vieques and Culebra (Figure 2-2). 
Field investigations began on October 4 and lasted until October 9. Wind and flood 
damage and success stories were gathered and local residents were interviewed. Power 
poles, as well as other infrastructure items, were also inspected to determine the effects 
of the storm. 
On October 6, the BPAT split into two groups, a wind investigation team (Wind Team) 
and flood investigation team (Flood Team). Ground investigations for both groups included 
visits to Jayuya, Adjuntas, and Utuado (Figure 2-3). On October 7, the Flood Team continued 
west investigating coastal and riverine flooding in Cabo Rojo, Rincón, Mayagüez, Aguadilla, 
and Arecibo. The Wind Team remained in the center of the island north of Ponce to observe 
wind damage and investigate reports of tornadic activity. On October 9, both teams flew to 
Culebra to inspect this newly designated FEMA Project Impact community.2 The BPAT team 
completed its deployment on October 10. 
2.4 Planning Regulations 
Planning Regulation 7 (building code) was first adopted by the Government of Puerto 
Rico in 1968 and was later amended in 1987. The .provisions on the minimum loads for 
calculation of [loads acting on] structures were completely revised, taking into consideration 
the requirements of the 1982 Uniform Building Code (UBC) and recommendations of the 
study carried out by the Commission on Earthquakes of the Engineers and Surveyors 
Association of Puerto Rico,. according to the amended regulations. As part of the 1987 
Planning Regulation amendment, Puerto Rico was identified as a seismic zone 3, requiring all 
new construction.single-family houses included.to be seismic-resistant. A design wind 
speed of 110 mph (fastest-mile) was recommended. Puerto Rico.s Regulations and Permitting 
Administration (Adminstración de Reglamentos y Permisos [ARPE]) regulates these 
provisions of Planning Regulation 7, which was in effect at the time Hurricane Georges struck 
2 FEMA.s Project Impact Program helps communities protect themselves from the devastating effects of natural 
disasters by taking actions that dramatically reduce the potential for disruption and loss to buildings and property. 
FEMA provides expertise and technical assistance from the national and regional levels (including other federal 
and state agencies) to individual communities to mitigate against natural hazard events and provide funding for 
the administrative support of these initiatives.
Building Performance Assessment: Hurricane Georges In Puerto Rico 2-5 
Section 2 INTRODUCTION 
FIGURE 2-2 Flyover routes from October 2 (in red) and October 3 (in blue). Map is not to scale. 
Source: The Perry Castañeda Library Map Collection.
2-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
INTRODUCTION Section 2 
FIGURE 2-3 Locations of ground investigation by the BPAT. Map is not to scale. 
Locations of Ground Investigations 
by the BPAT
Building Performance Assessment: Hurricane Georges In Puerto Rico 2-7 
Section 2 INTRODUCTION 
Puerto Rico. In late December 1998, the government of Puerto Rico adopted emergency 
regulations to repeal Planning Regulation 7 and adopt the 1997 Uniform Building Code 
(UBC) as the building code of Puerto Rico. 
2.5 Floodplain Management Regulations 
In August 1978, the Government of Puerto Rico joined the National Flood Insurance 
Program (NFIP). The NFIP was created by an act of the U.S. Congress to make flood 
insurance available to property owners in communities that agree to enact and administer 
floodplain management regulations meeting program requirements. Initial Flood Insurance 
Rate Maps (FIRMs) of Puerto Rico were issued in August 1978; the most recent updates were 
published in September 1996. 
The Government of Puerto Rico adopted NFIP-compliant floodplain management 
provisions under Planning Regulation 13 to regulate construction in Special Flood Hazard 
Areas (SFHAs) identified as flood zones on FIRMs. In coastal areas, this means that buildings 
must be adequately elevated and protected from the effects of high-velocity flood flow. In VZones, 
buildings must be elevated on piling (or column) foundations and the lowest 
horizontal structural member of the lowest floor must be at or above the Base Flood 
Elevation (BFE). In addition, the area below the building must be free of obstructions or 
enclosed by non-supporting breakaway walls intended to collapse under wind and water 
loads without causing damage to the foundation or the elevated portion of the building. 
In A-Zones, which are less likely to be affected by high-velocity flow, the top of the lowest 
floor of the building must be at or above the BFE and the areas below the BFE can be 
enclosed with non-breakaway walls. However, the area below the BFE can only be used for 
parking, access, and storage. These regulations require new and substantially improved 
buildings in floodprone areas to be built to reduce flood hazards. The Puerto Rico Planning 
Board and ARPE regulate Planning Regulation 13. 
2.6 Puerto Rico Seismicity 
Along with much of the Caribbean, Puerto Rico is subject to significant earthquake and 
tsunami risk. The written history of earthquake damage in Puerto Rico dates back to 1867 
when the first earthquake was recorded, with an estimated magnitude of 7.3 on the Richter 
Scale occurring off southeast Puerto Rico. In 1918, the island was hit by a magnitude 7.3 
earthquake approximately 9 miles off its northwest coast. The ensuing tsunami had wave 
heights approaching 19 feet and caused major damage. Reportedly, 116 people were killed, 
40 as a direct result of the tsunami. A minor earthquake also hit the island in 1922 [Earth 
Scientific Consultants]. The American Society of Civil Engineers Standard 7-95 (ASCE 7-95), 
Minimum Design Loads for Buildings and Other Structures, as well as the National 
Earthquake Hazards Reduction Program (NEHRP) 1997 Recommended Provisions, require all 
structures in Puerto Rico, including single family homes, to be seismic resistant. These 
documents have stricter requirements for seismic construction in Puerto Rico than Planning 
Regulation 7 (building code) that was in place when Hurricane Georges struck Puerto Rico. 
The recently adopted 1997 UBC is compliant with both the 1997 NEHRP and the seismic 
provisions of ASCE 7-95.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-1 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
3 Assessment and Characterization of Damages 
The general types of damages the BPAT observed as a result of Hurricane Georges in 
Puerto Rico are discussed below. More detailed descriptions of the damage observed are 
included in Sections 4, 5, 6, and 7. 
3.1 Wind Effects 
The National Weather Service (NWS) reported wind speeds from Hurricane Georges 
varying from 109 mph to 133 mph (3-second peak gust at a height of 33 feet) as it crossed the 
island of Puerto Rico. NWS recorded wind speeds at different airports using the Automatic 
Surface Observing System (ASOS). Since ASCE 7-95 uses 3-second gust wind speeds at 33 feet 
above ground over flat open terrain conditions, all data recorded under different conditions 
were transformed to the ASCE 7-95 averaging time and height for comparison purposes. Based 
on recorded data and BPAT observations, the wind speeds experienced in Puerto Rico during 
Hurricane Georges did not exceed the basic design wind speed of Planning Regulations 7.s 110 
mph fastest-mile (133 mph 3-second gust). In addition to this basic design wind speed, an 
overload factor of 1.3 for light structures and an importance factor of 1.15 for essential facilities 
are applied, resulting in a higher wind speed for failure. 
The siting of structures affected the wind forces that acted upon the building. Lower areas 
were sometimes shielded from winds by hills or mountains. Buildings on high exposed slopes 
appeared to receive higher wind speeds because of the speedup of the wind up the slopes of 
the hills or mountains (due to topographic effects and described in ASCE 7-95) (Figures 3-1 
and 3-2). The significance of these topographical effects is not recognized in Planning 
Regulation 7, but is accounted for in the newly adopted 1997 UBC. The 1997 UBC 
references ASCE 7-95 for the determination of wind speeds. These wind speeds may be 
adjusted to incorporate topographic effects on wind speeds. 
Doppler weather radar detected three possible tornado events in Vieques, Orocovis, and 
Jayuya. The output given by Doppler weather radar, which is based on algorithms, is 
interpreted by meteorologists who decide whether or not a tornado warning should be issued. 
Sometimes, a circulation detected by Doppler radar that occurs at great elevations may never 
touch ground. The BPAT members investigated building damage in and around these towns 
and found no evidence of tornadoes, such as debris spread in a radial manner and/or severely 
shredded or pulverized debris, indicative of a tornado on the ground.
3-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
3.2 Riverine and Coastal Flooding 
Flood damage was observed mainly along rivers in the west and central areas of Puerto 
Rico, including Utuado, Jayuya, Adjuntas, Mayagüez, Añasco, and Arecibo. Coastal flooding 
was noted along the western shore at Rincón and Mayagüez. Damage in these areas occurred 
to buildings constructed without sufficient elevation above the BFE. 
FIGURE 3-1 The abrupt change in topography in this community outside Loiza 
caused a speedup in the wind that flows over and around the buildings located on 
the hill beyond. The wind load provisions of Planning Regulation 7 did not account 
for wind speedup caused by abrupt changes in topography, and therefore 
underestimated wind loads on buildings situated on hills, mountains, or 
escarpments. 
FIGURE 3-2 Wind damage from Hurricane Georges to residential buildings in 
Puerto Rico. Blue FEMA tarps have been placed on many of the roofs that 
sustained damage.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-3 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
Flooding damage fell into two categories: buildings inundated by floodwaters that caused 
much of the building and contents to be wet, but no structural damage; and buildings with 
structural damage, where the foundations were undermined by floodwaters. Almost all flooddamaged 
homes fell into the first category. Figure 3-3 shows a typical non-elevated structure 
in a community located entirely in an SFHA that was damaged by Hurricane Georges. Figure 
3-4 depicts a flood control measure that protected homes on one side of the river. Figure 3-5 
is an example of the damage caused to the area along the river opposite the floodwall in 
Figure 3-4. Although these homes were severely flooded, they experienced minimal to no 
structural damage. Figures 3-6 and 3-7 illustrate cases where flooding undermined the 
building foundations. 
FIGURE 3-3 Typical non-elevated structures in a 
community located entirely in an SFHA. 
FIGURE 3-4 This flood gate located in Adjuntas prevented backwater from 
flooding homes located behind it; however, the wall contributed to flooding in the 
community located on the opposite side of the river, as shown in Figure 3-5.
3-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-6 Floodwaters eroded soil and undermined the foundation system of 
this building. 
FIGURE 3-5 Residential area on the opposite side of the river from the floodwall 
in Figure 3-4. The flooding in this area reached a depth of 5 feet.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-5 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-7 Riverbank erosion resulted in the undermining of the building 
foundations of a school (pink building) and house (white building) in Jayuya. 
FIGURE 3-8 Typical construction adjacent to and over the river. Note the debris 
trapped under the concrete foundation and between the framing. 
Siting of homes in floodprone areas, such as river and stream beds, was observed 
throughout Puerto Rico. Figure 3-8 illustrates a home constructed adjacent to and over an 
existing stream. Structures constructed in this manner are vulnerable to damage from 
floodwaters.
3-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-10 The top of the lowest floors of buildings in A-Zones must be at or 
above the BFE. Foundation walls below the BFE must be equipped with openings 
that allow the entry of flood waters so that interior and exterior hydrostatic 
pressures can equalize. 
NFIP regulations and Planning Regulation 13 require that the lowest floor of structures 
located in A-Zones must be elevated to the BFE. However, in some flooded areas many 
buildings were not elevated to the required elevation. In many cases, the flooded structures 
may have been built before the FIRMs were issued. Homes were damaged due to improper 
elevation in coastal areas (Figure 3-9). Proper elevation techniques for construction in AZones 
are presented in Figure 3-10. A comparison of some of the differences in NFIP 
requirements for construction in V-Zones and A-Zones is presented in Figure 3-11. 
FIGURE 3-9 Structure along the coast damaged by storm surge and 
wave action.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-7 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-11 Comparison of building foundation and elevation requirements in V-Zones and A-Zones. 
Buildings were not the only structures affected by the flooding of Hurricane Georges. 
Infrastructure, such as bridges and roadways, was also damaged. Three major bridges and a 
number of small bridges were washed-out and impassible. A bridge damaged by floodwaters 
outside Adjuntas is shown in Figure 3-12 and a severely damaged water treatment facility is 
shown in Figure 3-13. 
FIGURE 3-12 This bridge outside Adjuntas collapsed due to insufficient design to 
resist the effects of floodwaters.
3-8 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-13 Severely damaged water treatment facility located in the 
floodplain in Jayuya; floodwaters overtopped the concrete wall. 
3.3 Landslides 
Puerto Rico.s steep topography and shallow, sandy soils over bedrock make it susceptible 
to landslides. During Hurricane Georges, widespread rainfall in the more mountainous 
regions of the island resulted in numerous landslides that blocked and undermined roads, 
and even destroyed homes (Figures 3-14 and 3-15). This will become a greater problem in 
the future as more developments and houses are constructed in regions prone to such risks. 
A more detailed review and analysis of this problem needs to be undertaken. Figure 3-16 
illustrates problems with unrestricted development. Many single-family homes are located 
beneath a cut that is void of vegetation, making the slope susceptible to landslides. 
FIGURE 3-14 Aerial view of a now uninhabitable house caught in a landslide.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-9 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-15 A landslide inundated this house with up to 5 feet of soil. 
FIGURE 3-16 Development adjacent to a representative unprotected cut; the 
potential for future landslide activity exists.
3-10 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-17 Commercial concrete structures with no structural damage. These 
structures are located to the east of Old San Juan. 
3.4 Overview of Buildings Evaluated 
The BPAT investigated residential and commercial buildings that were affected by wind, 
riverine and coastal flooding, and landslides. These buildings can be categorized into four 
types of construction: 
n Concrete/masonry structures with concrete roof decks 
(residential and commercial). 
n Concrete/masonry structures with wood-frame roof structures 
(residential and commercial). 
n Combination structure, concrete foundation/first floor with 
wood-frame structure for the additional levels. 
n All wood-frame structures. 
The structural performance of buildings constructed of concrete/masonry with concrete 
roof decks was excellent. This was true for residential and commercial buildings. Residential 
buildings and homes constructed of concrete/masonry with wood-frame roof structures 
experienced widespread roof loss. 
The all wood-frame structures, almost exclusively residential construction, performed 
worse than all others and the greatest amount of destruction was observed in them. 
Residential buildings investigated ranged in age from post-WWII to current day construction. 
Most mid- to high-rise buildings inspected were constructed during and since the 1960.s. 
3.4.1 Concrete/Masonry Structures with Concrete Roof Decks 
Both residential and commercial buildings constructed of concrete/masonry with 
concrete roof decks were investigated. Figure 3-17 shows commercial buildings of concrete 
construction with concrete roof structures. These large buildings performed well structurally 
during Hurricane Georges. Many, however, experienced significant interior damage and 
property loss due to breach of the building envelope. Loss of exterior windows due to wind 
and windborne debris was the primary damage observed (Figure 3-18).
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-11 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-18 Commercial concrete structure with 
interior damage due to breach of building envelope 
(failed windows). Note: Plywood sheets were installed 
after the storm to cover broken windows; they were not 
present prior to the storm. 
The BPAT observed that single-family homes constructed of concrete, masonry, (or a 
combination of both) and with concrete roofs performed well with no structural damage 
(Figure 3-19). These structures were primarily one- and two-story buildings with reinforced 
concrete columns/piers and both reinforced and un-reinforced concrete masonry units 
(CMU) block pier foundations supporting elevated concrete floor slabs. 
For the purposes of this report, systems used to protect doors and windows from missiles 
(windborne debris) are referred to as .shutter systems.. Shutter systems observed on the 
island varied in material and included plywood sheeting, corrugated metal, and preengineered 
metal and plastic panel systems. In Puerto Rico, these temporary shutter systems 
are commonly referred to as .hurricane panels..
3-12 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-19 Residential concrete structure in the mountains north of Adjuntas 
with no structural damage following Hurricane Georges. 
The first floor of concrete/masonry buildings with reinforced concrete roof decks often 
were elevated a single story or more above the ground on minimally reinforced columns. As 
a result, they are at significant risk from collapse during a major earthquake. The successful 
performance of these buildings during Hurricane Georges appears to relate mainly to the 
dead load from the weight of the concrete roofs and walls that helped resist uplift and lateral 
wind loads. The size and spacing of reinforcing steel was noted by the BPAT on buildings 
under construction, and the connections appeared to be based solely on gravity loads and 
the minimum connections of reinforcing steel for gravity loads. The BPAT observed a general 
lack of attention to lateral loads in all residential construction. For wood-frame houses, this 
lack of attention was evident in the amount of hurricane damage they received. 
3.4.2 Concrete/Masonry Structures with Wood-Frame Roof Structures 
Buildings with walls constructed of concrete/masonry columns with masonry infill and 
wood-frame roof structures were observed. This construction type is commonly found in 
Puerto Rico. Buildings of masonry construction with wood roof framing have performed well 
in other hurricane-prone areas of the United States when a continuous load path is present 
to transfer wind-induced loads from the roof structure to the foundation. Generally, the BPAT 
found that there was no attention to a continuous load path (for wind or seismic loads) in 
the roof structures other than for gravity loads. The sill plate atop the masonry wall was 
generally attached by extending reinforcing steel through a hole bored in the sill plate and 
bending the steel to prevent withdrawal, uplift, or displacement of the sill plate. 
Most roofs inspected were gable roofs; the remainder were low-slope (flat roofs) and 
hipped roofs. Figure 3-20 represents a single-family home with a wood-frame gable roof 
structure that experienced a typical roof failure. Failure of roof structures at gable ends has 
been well documented following previous hurricanes, especially when insufficient attention 
has been paid to connection details at the masonry walls or to bracing the gable end wall. 
This was the case in Puerto Rico.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-13 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-20 Aerial view of a residential concrete/masonry structure with a 
wood-frame roof structure; only the roof rafters remain. The wood nailers and 
metal panels were blown off. 
3.4.3 Combination Structures, Concrete/Masonry and Wood-Frame 
Structures 
This construction type was observed almost exclusively in single-family home 
construction. Concrete columns often supported an elevated concrete slab. CMU block, 
typically 6-in thick, was used to enclose the lower floor or crawl space area. Wood framing 
completed the walls and roof structure above the first level. Wood framing was generally 
inadequate. Nominal 2-in by 3-in lumber was sometimes used for studs. Nominal 2-in by 4-in 
studs, when used, were often spaced up to 4-feet on center. The studs were generally 
connected to the wall system by nailing to a bottom plate or sometimes directly to the 
subfloor. Typically, no connection other than nailing was made from the studs to the floor 
system. When exterior grade plywood was used as sheathing, it generally did not overlap the 
band joist. Top plates frequently were made of single, rather than double, 2-in by 4-in 
members. Rafters generally were supported directly over the studs. No connection other 
than nailing was made from the walls to the rafter or truss system. Figure 3-21 shows this type 
of single-family home. While wood-frame construction generally performs well in 
earthquakes, the other building elements commonly found in Puerto Rico.long slender 
columns supporting the structure.can lead to the collapse of these structures in a significant 
earthquake.
3-14 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ASSESSMENT AND CHARACTERIZATION OF DAMAGES Section 3 
FIGURE 3-21 A combination residential concrete/masonry structure with an 
elevated second-floor concrete slab and a wood-framed upper level. Note the 
lack of damage to the concrete/masonry section of the house and the damage to 
the wood-frame portion. 
In Figure 3-22, the concrete/masonry building is under construction. Details regarding 
concrete columns, masonry block, and typical reinforcing steel were observed and noted. 
FIGURE 3-22 A residential concrete/masonry structure that is under 
construction. The photograph illustrates this common building practice: concrete 
columns with unreinforced masonry block infill walls. This is not seismic resistant 
construction.
Building Performance Assessment: Hurricane Georges In Puerto Rico 3-15 
Section 3 ASSESSMENT AND CHARACTERIZATION OF DAMAGES 
FIGURE 3-23 A residential wood structure located on the hilltops west of Ponce 
destroyed by wind. The roof system has been removed and the wall system 
partially collapsed. 
3.4.4 All Wood-Frame Structures 
All wood-frame structures were almost exclusively limited to single-family homes. These 
structures were set atop concrete, masonry, or wood piers and foundations. The load path 
for wind- and seismic-induced loads from the foundations to the floor systems ranged from 
bolted steel band connectors to no connectors at all. The walls in these houses were 
constructed of nominal 2-in by 3-in or 2-in by 4-in lumber. Wall frames were weak with studs 
spaced up to 4-feet on-center. Sill and bottom wall plates were inadequately fastened to slabs 
or supporting floors. Stud wall construction contained little to no lateral bracing and only 
single member top plates. Roof support systems typically were nominal 2-in by 4-in members 
at 4-feet spacing with nominal 1-in by 3-in nailers supporting metal roof panels. Only a very 
small number of these structure types had a continuous load path from the roof system to 
the foundation. Figure 3-23 shows a typical wood-frame home that sustained significant 
damage during the hurricane.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-1 
Section 4 STRUCTURAL PERFORMANCE 
4 Structural Performance 
The BPAT inspected the structural performance of three primary construction types: 
reinforced concrete, reinforced masonry, and wood-frame. Inspections focused on the 
performance of single-family buildings. Isolated examples of success and failure in 
commercial buildings observed during field investigations were also documented. 
It is important to state that wind speeds experienced on the island were not of the 
strength to test the reliability and adequacy of the reinforcing steel used in all of the 
reinforced and partially reinforced masonry walls. A more significant wind event striking 
Puerto Rico would likely have resulted in even more failures than were observed. 
Planning Regulation 7 of Puerto Rico (building code) required strict practices for different 
primary construction types. Guidelines that were in place under Planning Regulation 7 for 
new construction accounted, at least partially, for wind and seismic loads, but these 
guidelines had not been consistently complied with or enforced effectively. Most of the 
damage the BPAT observed was directly related to design inadequacies and the lack of 
enforcement of Planning Regulation 7. Additional damage observed was related to poor 
quality of workmanship of self-built homes. 
The 1987 amendment of Planning Regulation 7, which was in place at the time Hurricane 
Georges struck Puerto Rico, included wind speed design requirements to 110 mph (fastestmile) 
for all buildings and design wind pressures for walls of 30 lbs. per square foot (psf) and 
for roofs up to 60 psf for residential buildings. Seismic provisions for commercial buildings 
and one- and two-family homes were also clearly identified. The failure to comply with and 
enforce this building regulation in all residential building construction resulted in 
widespread damages from Hurricane Georges. A major seismic event on the island could 
cause even more damage, since most of the elevated residential structures observed.even 
those that performed well during the hurricane.are not seismic resistant because they were 
constructed with inadequate lateral force resisting systems. The adoption and strong 
enforcement of the 1997 UBC should address many deficiencies observed by the BPAT. 
In general, concrete/masonry structures performed well under the wind loading of 
Hurricane Georges. Structural damage to concrete and masonry structures from floodwater 
was usually limited to the building foundations as a result of erosion, scouring away of 
supporting soil, and the impact of waterborne debris. 
Wood-frame structures generally performed poorly under wind loads generated by 
Hurricane Georges and damage was extensive throughout the island. A continuous load path 
from roof system to foundation was essential for building survival. Figure 4-1 illustrates a 
continuous load path for a wood-framed structure. The success of concrete and masonry 
structures illustrated the importance of a continuous load path while the failure in woodframe 
structures illustrated the lack of proper wood construction techniques to provide an 
adequate and continuous load path. Figures 4-2 and 4-3 compare and contrast the success 
and failure of concrete and wood-frame building systems with similar wind exposure.
4-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-1 If a building has a continuous load path, forces and loads acting on any portion of the 
building will be transferred to the foundation of the building. This transfer occurs through building 
structural members (i.e., columns and beams) and the connections between these members. In this 
figure, the load path from the roof structure to the foundation is illustrated for an elevated, two-story 
wood-frame building.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-3 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-2 A residential community constructed of concrete and masonry 
buildings with concrete roof structures. This community, located to the west of 
Luquillo experienced no complete building failures. The eye of the hurricane 
passed to the south of this community, placing it in the strongest wind quadrant of 
the hurricane. 
FIGURE 4-3 A residential community constructed of wood-frame structures only. 
This community located to the north of Canóvanas, experienced significant 
structural damage and failure to almost all of its buildings. The eye of the 
hurricane also passed to the south of this community, which is located 
approximately the same distance from the path of the hurricane as the 
community in Figure 4-2.
4-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
4.1 Reinforced Concrete 
The BPAT observed no structural damage to reinforced concrete residential or mid- and 
high-rise buildings. It was obvious that mid- and high-rise buildings received considerable 
attention from design professionals. Where concrete frames were observed, infill walls ranged 
from fully glazed to CMU (typically 6-in standard block) to metal and wood stud walls. 
Exterior cladding was stucco (trowel-applied cement plaster typically ½-in thick), Exterior 
Insulating Finishing Systems (EIFS), and block, brick, or stone veneer. These wall and 
cladding systems exhibited varying degrees of success or failure, as discussed in Section 5.2. 
4.1.1 Reinforced Concrete Mid- and High-Rise Buildings 
The lack of structural damage to reinforced concrete mid- and high-rise buildings was 
probably related to the role of the design professional in their construction as well as the fact 
that Hurricane Georges was not a design event. However, several buildings received 
considerable damage to the building envelope and are discussed in Section 5. The BPAT did 
not determine the seismic resistance of the mid- and high-rise buildings it observed. 
Residential reinforced concrete/masonry structures with concrete roof decks performed 
well regardless of wind direction or velocity. Concrete/masonry structures with wood wall 
and roof framing generally performed poorly, regardless of siting. High velocity flood waters 
caused structural damage in SFHAs. Lower velocity floodwaters (also in SFHAs) inundated 
houses, causing considerable damage inside the buildings. Several concrete and masonry 
structures were left unstable from riverine and coastal erosion and mountain landslides 
(Figure 4-4). 
FIGURE 4-4 Concrete residential structure with foundation damage caused by a 
landslide. Note unstable footings (circled).
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-5 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-5 Fire station in Adjuntas. 
4.1.2 Reinforced Concrete Essential Facilities 
The BPAT inspected two fire stations, one in Adjuntas and the other on the island of 
Culebra, located approximately 20 miles east of the main island. Both fire stations had 
concrete roof decks. The stucco finish on both buildings prevented a direct observation of 
the wall systems that reportedly consisted of concrete columns with CMU infill. These 
structures also had open security grilles in the truck bays rather than large rolling doors. 
Neither station sustained structural damage during the hurricane. The Adjuntas fire station, 
which completed construction in 1998, featured a small percentage of exterior windows and 
an emergency electrical generator that was protected and enclosed within the building 
envelope (Figure 4-5). The BPAT was unable to determine the seismic resistance of either 
fire station. 
4.1.3 Concrete/Masonry Structures with Concrete Roof Decks 
Reinforced concrete buildings (single-family homes) with reinforced concrete roof decks 
generally did not sustain structural damage (Figure 4-6). First floor walls in reinforced 
concrete residential buildings were usually 6-in to 8-in thick and constructed of reinforced 
concrete columns with masonry infill, or were solid concrete walls. CMU walls had varying 
amounts of reinforcement within the cells. Roof decks typically were flat and constructed of 
reinforced concrete. Many were exposed concrete with no roof covering. This structure type 
performed extremely well. Even buildings with unprotected wall openings did not 
experience structural damage. 
The most significant damage observed for this type of construction centered around 
building envelope issues. Buildings (specifically single-family homes) typically had 4-in 
aluminum jalousie louvers (Miami windows) that were vulnerable to water infiltration during 
high wind events and allowed development of high internal pressure. Shutter systems are 
discussed in more detail in Section 5.4. 
Residences constructed of reinforced concrete and a wood roof structure generally did 
not perform well during Hurricane Georges. Buildings without shutter systems were often 
breached, resulting in pressurization of the building and blown-off roofs. When shutters were
4-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-6 Residential home constructed of reinforced concrete and masonry 
with a reinforced concrete roof deck in the mountains outside Adjuntas. 
FIGURE 4-7 Typical roof system failure between wooden roof system and 
concrete or masonry wall system. 
observed to have been properly designed and installed, the roof framing and roofing typically 
were inadequate for lateral and uplift pressures, even without the added pressure from 
internal pressurization of the building. 
4.2 Masonry 
The BPAT investigated a limited number of residential and nonresidential masonry 
buildings. Most of the buildings observed had wood-frame roof structures that were damaged 
during the hurricane (Figure 4-7).
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-7 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-8 Termite-damaged wood purlin attached to metal roof panel. The 
entire roof system of this building failed and is shown in Figure 4-9. 
4.2.1 Masonry Commercial Buildings 
The BPAT observed several commercial buildings located on the island. Although many of 
them weathered the storm with minimal to no damage, this was mainly due to the siting of 
the buildings in areas of little wind and the buildings. relatively short un-reinforced masonry 
walls. The BPAT concluded that the commercial masonry buildings observed did not 
experience design level winds. Nonresidential buildings were observed with masonry wall 
systems and wood-framed roofs. Some roof failures in these buildings were the result of a 
poor connection between the wood-roof framing and the masonry walls. Termite damage 
was also observed in some residential wood-frame buildings, but the problem did not appear 
to be widespread. Figure 4-8 shows a termite-infested roof member that failed during the 
hurricane. The wood purlin and metal roof covering was separated from a building 
constructed with masonry walls and a wood-frame roof structure (Figure 4-9). Termiteweakened 
wood members were likely the starting point of this roof failure. Figure 4-10 is a 
close-up of the typical nailed connection between the purlins and the supporting rafters.
4-8 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-10 Nailed roof structure connection from church in Figure 4-9. 
FIGURE 4-9 Masonry wall church that lost roof purlins and its corrugated metal 
roof. Nails were the only connections used to resist wind loads. The gable ends of 
this church were unsupported except for purlins resting in the masonry.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-9 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-11 Typical nail withdrawal failure in a wood-frame structure 
supported by a masonry wall with little uplift capacity at the connection. 
4.2.2 Residential Concrete/Masonry Structures with Wood-Frame Roof 
Structures 
Successes and failures in masonry residential buildings were the same as those observed 
for concrete buildings. Success depended upon the existence of a continuous load path from 
the roof structure to the foundation for lateral and uplift loads. Conversely, wood-frame roof 
structures typically did not have a continuous load path to the foundation and widespread 
failure due to wind-induced uplift was observed. Figure 4-11 shows a typical nail withdrawal 
failure of a wood-frame roof/masonry wall connection. 
Rafters ranged from nominally sized lumber, 2-in by 4-in or 2-in by 6-in that spanned 
10 feet to 16 feet, and were spaced from 2-feet to 4-feet on center. Rafters were typically toenailed 
to the sill plate and not connected with hurricane clips or straps. The ridge rafters 
bore on a ridge beam (although sometimes the ridge beam was omitted). No connection 
other than nailing was generally made at the ridge line. Self-built trusses were also used. 
Similar to rafters, these trusses were connected only by nails to the sill plate. These trusses 
were sometimes manufactured by nailing the truss members together by toe-nailing, or by 
use of nominal 1-in lumber, or plywood for gusset plates. These self-built trusses were 
inadequate for the wind loads. As a result, widespread wood-frame roof failures were 
observed (Figure 4-7). 
Corrugated metal was commonly used as a roof covering, typically fastened to nominal 
1-in boards or 2-in by 4-in boards used as nailers to the rafters. Nailers were generally 
attached with two nails (16 penny or smaller) at the rafters. The trusses were generally 
unbraced or minimally braced for lateral loads and had little or no shear capacity from lateral 
loads. The attachment of the nailers for the corrugated metal roofing was completely 
inadequate for the uplift loads on the roofing. Since the majority of these homes had Miami 
windows, considerable internal pressures also acted on the roof system.
4-10 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
4.3 Wood-Frame Buildings 
The BPAT investigated a number of residential wood-frame buildings. Very few of them 
survived the storm with little or no structural damage. 
4.3.1 Commercial Wood-Frame Buildings 
No new commercial buildings constructed from wood-framing were observed. As 
anticipated, many older, nonresidential buildings were damaged due to the lack of both uplift 
and lateral load paths from the roof system to the foundation. 
4.3.2 Residential Wood-Frame Buildings 
The BPAT observed many self-built single- and two-story residences. Self-built buildings 
are those that did not appear to be built to commonly accepted building practices. Very few 
appeared to have been designed or constructed to the current building regulations. As a 
result, a large number of wood-frame houses were structurally damaged during the 
hurricane. Houses built to current building regulations or newer codes weathered the storm 
successfully with minimal structural damage, but again it is worth noting that most of these 
houses were not exposed to design wind conditions. 
Some residents installed hurricane clips as part of their mitigation efforts after hurricanes 
in 1995 and 1996. Figure 4-12 shows positive mitigation efforts implemented in a wood-frame 
house on the island of Culebra in 1996, as observed after Hurricane Georges. Utilization of 
clips and straps, however, was not typical in wood-frame buildings in Puerto Rico. 
FIGURE 4-12 Hurricane clips installed in a wood-frame house on Culebra. 
Improperly sized and spaced lumber was used throughout the self-built homes inspected. 
Some lumber appeared to be salvaged. Even in homes where clips were used, they were 
often installed with the incorrect number and size of nail. Wind completely destroyed a 
building constructed by a contractor only two months before Hurricane Georges occurred.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-11 
Section 4 STRUCTURAL PERFORMANCE 
Traditional and inadequate nailing techniques were used on this structure while state-of-theart 
clips, brackets, and fasteners were found lying beneath the building. Clips and hangers 
that were used did not employ the proper nails and failure resulted (Figure 4-13). 
FIGURE 4-13 Example of the failure of wood member in the floor joist hanger 
due to the use of improper nails. The hurricane clip was used to secure the floor 
joist to the support beam. This house was located on the island of Culebra. 
4.3.2.1 Residential Wood-Frame Walls 
Framing layout and construction techniques used in almost all self-built wood-frame 
homes were not in compliance with Planning Regulation 7. Wall framing was constructed 
from nominal 2-in by 3-in and 2-in by 4-in studs. These studs were not properly supported 
laterally and not connected to the sill, bottom, or top plates with straps or connectors (Figure 
4-14). The sill plate was inadequately (and often not) connected to the floor system with 
fasteners capable of resisting lateral and uplift forces. Top sill plates typically were single 
nominal 2-in by 4-in members that support the roof structure for gravity loading only. Nails 
appeared to be the primary connector used, with most connections being .toe-nailed.. End 
column (nominal 4-in by 4-in) members were observed in the wall sections of some woodframe 
houses (Figure 4-15).
4-12 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-15 Wood wall column that failed at connection to sill plate. This 
building was only two months old but was only partially constructed with clips, 
straps, and fasteners. The proper column fastener in the photograph was found 
unused beneath the house. This column was from the same house presented in 
Figure 3-13. 
FIGURE 4-14 Example of wood-frame wall construction that failed during 
Hurricane Georges. This building was not constructed with any hurricane clips 
or straps.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-13 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-16 Typical wooden roof structure with metal roof panels above. Nails 
connected the metal panels to the nailers and the nailers were nailed to 
the joists. 
4.3.2.2 Residential Wood-Frame Roof Structures 
The wood-frame roof structures discussed in Section 3.4 were found to be of poor quality 
construction and inadequately designed and constructed to withstand lateral and uplift wind 
forces. A majority of the wood-frame roof structures observed were gable ended; some of 
which had a peak with no ridge rafter. 
Roofs were constructed of rafters, self-built trusses or pre-manufactured trusses. Rafter 
roof systems typically used nominal 2-in by 4-in to nominal 2-in by 6-in members. Lateral 
support or bracing was only provided by nominal 1-in by 3-in to nominal 1-in by 6-in nailers. 
Roof rafters and trusses were spaced on intervals ranging from 2-feet to 4-feet on center. Roof 
nailers for metal roof panels were observed on most wood-framing at 3-feet to 4-feet on 
center (Figure 4-16). Nailers did not typically provide adequate load capacity for the 110 mph 
design wind indicated in the 1987 amendment to Planning Regulation 7. In addition, the 
nailer/joist connections and the nailer/rafter connections observed generally were only 
connected with one or two nails. This simple nailed connection does not provide adequate 
resistance to shear and uplift forces that may be experienced during a high wind or seismic 
event. Figure 4-17 shows a typical self-built, wooden roof truss. 
2-in by 4-in 
2-in by 4-in 
1-in by 4-in 
1-in by 4-in 
24-in 
48-in
4-14 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-18 Example of a non-engineered connection between the building 
foundation (concrete column) and the floor system. The wooden floor beam is 
connected to foundation rebar with an improper nailed connection. 
4.3.2.3 Residential Wood-Frame Floor Systems and Foundation Connections 
The wood-frame buildings the BPAT inspected had varying floor systems and floor systemto-
foundation connections. Many floor systems that remained in place after the wood-frame 
building constructed above was destroyed had minimal connections between the floor 
system and the foundation. Success of these connections is believed to be due to the failure 
of the roof and walls before the failure of these typically non-engineered connections 
between the floor system and the foundation (Figure 4-18). In a few homes, engineered floor 
system-to-foundation connections were observed (Figures 4-19 and 4-20). 
FIGURE 4-17 Example of a self-built, wooden roof truss.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-15 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-20 Example of a successful wood connection between support beam 
and floor joists. This is the same house shown above in Figure 4-19. 
FIGURE 4-19 Example of an engineered connection between the floor beam and 
a concrete column (concrete column is enclosed in plywood). Vertical members 
(identified by arrows) provide continuous load path from floor joist to floor 
beams. Floor beams are connected to concrete columns with metal 
straps (circled). This house was located on the island of Culebra.
4-16 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-21 Wood-frame house with metal roof covering with hold-down 
cables that run parallel (see arrows) and perpendicular to the roof ridge line. 
This house was set atop a ridge that experienced significant winds. The lack of 
damage can be attributed to the extra care taken in fastening down the 
corrugated metal roofing. The strapping would not have prevented buckling of 
the roofing or uplift at the eave. 
4.4 Hold-Down Cables 
Tiedown or hold-down cables were used on some self-built wood-frame homes in Puerto 
Rico as a low-cost mitigation attempt. Typically, these cables were connected directly to the 
foundation of the structure although some cables were observed to have their own 
anchorage away and separate from the structure. Although there may have been exceptions, 
buildings with hold-down cables survived the effects of Hurricane Georges, but they remain 
largely untested during design wind conditions. In addition, there has been no engineering 
analysis of the effects of cable tiedown systems on load paths and structural and nonstructural 
building components. Hold-down cables are not expected to be effective unless the cables 
are designed and installed by an engineer or architect. 
A majority of hold-down cables observed crossed over the ridge-line of the roof of the 
house at 10-foot spacing. A smaller percentage was observed running parallel to roof ridgelines 
at 4-foot to 6-foot spacing as illustrated in Figure 4-21. The hold-down cables ranged 
from single strand steel wire to multi-strand steel cables.
Building Performance Assessment: Hurricane Georges In Puerto Rico 4-17 
Section 4 STRUCTURAL PERFORMANCE 
FIGURE 4-22 Residential building supported 
atop tall, unbraced concrete columns. This type 
of unbraced support column was common in 
many areas. 
4.5 Structural Seismic Considerations 
Seismic load designs for commercial buildings and one- and two-family homes were 
addressed in Puerto Rico.s 1987 amendment to Planning Regulation 7. For one- and twofamily 
homes, seismic design is required for structural elements, but is not for the 
engineering of nonstructural building elements. For commercial buildings, the amendment 
addressed both topics, structural and nonstructural seismic design. 
Nonresidential buildings were not investigated for compliance with the 1987 amendment 
to Planning Regulation 7 and the current structural seismic guidelines of the 1997 UBC. Oneand 
two-family homes, however, were investigated for their ability to sustain a seismic event. 
Inspections revealed that most of these homes constructed of concrete, masonry, and wood 
appeared to lack the lateral stability necessary to survive a design seismic event. Many 
residential buildings were constructed on piles and columns with no visible lateral bracing. 
Connections between foundation systems and the building did not appear to have moment 
capacity required to withstand lateral forces induced by a design seismic event (Figure 4-22). 
shows an elevated residential building with no lateral support bracing its long columns. 
Figure 4-23 is a close-up of one of the footings for the tall columns shown in Figure 4-22. This 
type of small footing .setting. atop a rock outcropping was typical for houses built 
on hillsides.
4-18 Building Performance Assessment: Hurricane Georges In Puerto Rico 
STRUCTURAL PERFORMANCE Section 4 
FIGURE 4-23 Footing for tall columns in Figure 4-22. This footing is not 
adequately anchored to the supporting rock to resist lateral forces that may be 
induced during a design seismic event.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-1 
Section 5 BUILDING ENVELOPE PERFORMANCE 
5 Building Envelope Performance 
Good structural system performance is critical to avoiding injury and minimizing damage 
to a building and its contents. It does not, however, ensure occupant or building protection. 
Good performance of the building envelope is also necessary. The envelope includes exterior 
doors, non-load bearing walls and wall coverings, roof coverings, windows, shutters, and 
skylights. Historically, poor building envelope performance is the leading cause of damage to 
buildings and their contents during hurricanes. 
5.1 Doors 
The BPAT observed a limited number of catastrophic door failures. However, in many 
cases where the doors were weak, the entire wall failed before the door assembly itself failed. 
Wind-driven water infiltration between the door and frame was a common problem. Most 
door assemblies observed did not have weatherstripping, and when it was present it 
provided limited resistance to rain driven by high winds. 
Exterior door failure has two important effects. First, failure can cause a sudden increase 
in internal air pressure, which may lead to exterior wall, roof, interior partition, ceiling, or 
structural damage. Second, wind can drive water through the opening, causing damage to 
interior contents and finishes. Essentials to good door performance include: product testing 
to ensure that sufficient factored strength to resist design wind loads exists; suitable 
anchoring of the door frame to the building; and for glazed door openings, the use of 
laminated glass or shutters to protect against windborne missile damage as discussed in 
Section 5.4. Missiles are both natural and man-made. Natural missiles include tree limbs, and 
man-made missiles include items such as building debris, fence debris, refuse containers, and 
lawn furniture. 
5.1.1 Glass Doors 
A variety of problems with glass doors were observed, including blow-out/blow-in of the 
door frame and glazing (Figure 5-1), door breakage and loss of glazing from its frame 
(Figure 5-2), and disengagement of sliding doors from their tracks. These problems were 
caused by over-pressurization or missile impact.
5-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-1 This sliding glass door and window assembly in a hotel room was 
7¹ 2" high and 14¹ long. The head of the frame was attached with four pairs of 
#12 or #14 screws in plastic sleeves. The sleeves pulled out and the entire length 
of the frame was pushed inward, resulting in substantial glass breakage. This 
building was located on Isla Verde in San Juan. 
FIGURE 5-2 Missiles broke 
this wood/glass door and 
several adjacent window 
panes.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-3 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-3 A missile traveling right to left struck the window louver. The door 
frame was attached by fasteners into wooden plugs that had been set into holes 
drilled into concrete. Once the louver failed, the door frame failed. 
5.1.2 Personnel Doors 
The BPAT observed few instances of door or door frame failure. However, Figure 5-3 
illustrates a metal door that was blown out when the frame anchors pulled out. The door was 
blown out after the louvered window on the building failed, allowing an increase in internal 
air pressure.
5-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-4 The security grille on this fire station offers greater wind 
performance reliability than a solid door because very little air pressure is applied 
to it during high winds. This fire station is located on the island of Culebra. 
5.1.3 Security Grilles, Rolling (Overhead) and Garage Doors 
Rolling doors and garage doors frequently perform poorly during high winds. In several 
instances observed in Puerto Rico, large openings were protected with security grilles, rather 
than rolling or garage doors (Figure 5-4). Very little load is applied to security grilles during 
high winds because of the large amount of net free open area. As a result, security grilles 
performed very well. Depending on the grilles, security grilles may stop large airborne 
missiles. It is important to note that areas with security grilles must be designed as open 
structures (without a building envelope). This will normally increase wind pressures acting 
on the structural frame of the building, as well as components and cladding.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-5 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-5 The gypsum wallboard was blown off this interior partition after the 
exterior non-load bearing wall was blown away, allowing an uncontrolled, rapid 
increase in internal air pressure. 
5.2 Non-Load Bearing Walls, Wall Coverings, and Soffits 
Non-load bearing walls and wall coverings generally performed well during Hurricane 
Georges. The BPAT did observe several types of problems however. 
Non-load bearing walls (or door or window assemblies) that fail can cause extensive 
interior damage because of the development of high internal air pressure and/or wind-driven 
water infiltration. Figure 5-5 shows the damage that occurred when a portion of the exterior 
envelope failed. Composite wall panels and their connections, exterior insulation finish 
system (EIFS), and other types of exterior wall coverings should be tested to ensure the 
components have suitable strength.
5-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-6 Rain entered this hospital on Culebra after a water tank struck the 
metal wall panels. 
5.2.1 Non-Load Bearing Walls and Soffits 
The BPAT observed three types of non-load bearing walls: metal panels over light-gauge 
steel framing, EIFS, and composite wall panels. Problems resulting in water infiltration were 
observed with each type and are discussed below. 
Metal panels over light-gauge steel framing were the most common non-load bearing 
walls observed. The BPAT noted the loss of metal panels due to an insufficient number of 
panel fasteners. In one instance, metal panels at the gable end of a building were damaged 
when a rooftop water tank blew off and struck the side of the building (Figure 5-6). 
A problem with EIFS at an ocean front high-rise was also observed. It appeared that the 
exterior wall stud tracks were insufficiently attached (Figure 5-7). Failure of the wall system 
resulted in substantial interior damage. 
Buildings clad in EIFS often provide a false sense of security since they appear to be clad 
in concrete, but may or may not be backed by concrete or masonry. When EIFS is used as a 
covering over concrete, as shown in Figure 5-11, this is not an issue. However, when EIFS is 
not applied over concrete, as shown in Figure 5-7, the building could be mistakenly 
construed as offering a safe area of refuge from high winds. EIFS applied on a steel or woodframe 
building as the exterior wall is not an as reliable building envelope as a concrete wall in 
resisting high winds and missiles. An EIFS not backed by concrete or masonry may be 
identified by a hollow sound when a person bangs on the panel or by a deflection when a 
person pushes the panel. 
The BPAT observed two buildings with composite wall panels composed of thin metal 
sheets bonded to a cardboard honeycomb core. The panels were attached with screws from 
the metal framing into the interior metal skin. On one building, the panels were also used as 
the soffit. In both buildings, the panels blew off because of insufficient strength of the 
connections between the composite panels and the structural frame of the building 
(Figure 5-8).
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-7 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-7 This EIFS wall system was composed of synthetic stucco over 1-in 
thick expanded polystyrene insulation (EPS) over a layer of exterior gypsum 
board over 6-in deep steel studs, with a layer of gypsum board on the interior 
side of the studs. Fiberglass batt insulation was installed within the stud cavity. 
There were several different planes of failure. Insufficiently attached stud tracks 
appeared to have been the initial failure point. This building was located on 
Isla Verde. 
FIGURE 5-8 Several composite panels blew off from the fascia and soffit of this 
building at the airport on Isla Grande. Although several screws were installed, 
the metal into which they were driven was too thin to develop sufficient blow-off 
resistance to withstand the wind loads.
5-8 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
5.2.2 Wall Coverings 
The BPAT observed four types of wall covering problems: 
n Loss of stucco applied over cast-in-place concrete. 
n Problems with EIFS coverings. 
n Ceramic tiles that were blown off. 
n Problems caused by wind scour. 
None of these problems resulted in water infiltration; however, with the exception of 
wind scour, failure of the wall covering resulted in additional debris being added into the 
wind field. 
The loss of stucco applied over cast-in-place concrete was the most common problem 
observed with wall coverings (Figure 5-9). Rather than cast concrete with a relatively flat and 
smooth surface, traditional practice in Puerto Rico has been to cast the concrete rough, as 
shown in Figure 5-10, and apply a stucco finish. 
FIGURE 5-9 The stucco was blown off the corner area of this wall, where the 
suction pressures were high. Note the rough texture of the concrete.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-9 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-10 This house is under construction. The surface of the concrete is 
very rough because the plywood form (which is lying down on the ground) was 
used repeatedly. The rough texture will be compensated for with a stucco 
surfacing. 
While stucco loss had only minor effects to the buildings where it was applied, the 
windblown debris could have traveled substantial distances and damaged other buildings. 
This was a particular problem when stucco debris was blown off of tall buildings. Instead of 
relying on stucco to provide an attractive wall surfacing, the quality of the cast-in-place 
concrete and CMU construction should be improved so that the concrete or CMU can be left 
exposed or painted. This would eliminate the missile problems that resulted when stucco 
was blown away and became airborne. 
The BPAT observed an EIFS covering consisting of synthetic stucco applied over two 
layers of EPS over concrete. There was a superficial bond between the two EPS layers (Figure 
5-11). Ceramic tiles were blown off of concrete spandrel panels on a high-rise building 
(Figure 5-12) and wind scour caused some exterior paint finish damage (Figure 5-13).
5-10 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-12 A mortar skim coat was applied over the concrete, and the 
ceramic tiles were set in to the mortar. The primary failure plane was between 
the mortar and concrete. 
FIGURE 5-11 At this EIFS covering, the synthetic stucco appeared to be welladhered 
to the outer EPS layer, but there appeared to be minimal bonding 
between the two EPS layers. In at least the lower portion of the wall, the first 
layer was attached with mechanical fasteners deeply recessed into the foam. The 
delamination occurred near the corner of the building, where the suction 
pressures were high.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-11 
Section 5 BUILDING ENVELOPE PERFORMANCE 
5.3 Roof Coverings 
Metal panels and concrete (either exposed or covered with a liquid-applied membrane) were 
the most common types of roof coverings found on residences. Commercial buildings typically 
were covered with metal panels or built-up membranes. Several other types of roof coverings were 
also observed. 
Historically, damage to roof coverings is the leading cause of building performance problems 
during hurricanes. In the rains accompanying a hurricane, water entering the building through 
damaged roofs can cause major damage to the contents and interior. These damages frequently 
are more costly than the roof damages themselves. 
5.3.1 Metal Panels 
The BPAT observed a variety of architectural and structural metal panels. Corrugated 
galvanized steel with exposed fasteners was the most common type found on residences. These 
panels generally were fastened with smooth- or screw-shank nails (Figure 5-14). With few 
exceptions, the spacing of fasteners along side laps, eaves, hips, and ridges was insufficient 
(Figure 5-15). 
FIGURE 5-13 This house was located on a mountain top that experienced very 
high wind conditions. The paint scoured off at some of the soffit areas and along 
the recessed wall.
5-12 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-15 Only a single row of fasteners were installed along the eave and 
along each side of the ridge. The side laps are insufficiently attached and are 
lifting in a few areas. The end lap is too far away from the first row of 
fasteners.another nailer should have been installed. Clips between the joists and 
wall were retrofitted prior to the hurricane; however, enhanced attachment of 
the metal roofing was not performed as part of that work. As a result, several of 
the metal panels were blown off. 
FIGURE 5-14 The nail attaching this corrugated metal panel partially backed-out. 
Screws are much more resistant to back-out. Nail back-out is a problem with 
metal panel systems because of the large number of load cycles and large amount 
of deformation the panels can experience during a hurricane. Elsewhere on this 
roof, some of the panels were blown off.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-13 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-17 At this house, a framing member was run up the rake, which 
allowed the metal panels to be fastened between the nailers (purlins). However, 
the rake member must have sufficient strength to resist design uplift loads, which 
does not appear to be the case with this member. Rather than installing a metal 
edge flashing, these metal panels simply were cantilevered beyond the rake 
framing, providing a loose edge that is susceptible to lifting and peeling during high 
winds. Other deficiencies that are noted in this photograph include incorrect 
nailing of roof material to rake member and inadequately sized and spaced nailers. 
FIGURE 5-16 The metal panels along this rake were insufficiently fastened. A 
framing member was not run up the rake. 
In some instances, a framing member was not provided along rake overhangs. Instead, the 
nailers were simply cantilevered and the metal panels were just attached at each nailer (Figure 5- 
16). With a continuous rake framing member, as shown in Figure 5-17, the metal panels can be 
attached with closely-spaced fasteners. Panel fasteners should be closely spaced along the rake 
because of the extremely high uplift forces that occur in this area during a hurricane.
5-14 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
Corrugated panels as well as other panel system designs frequently blew off the framing. 
However, in many instances framing failure caused the panel loss. 
In addition to the interior water damage that occurs upon blow-off of metal roof panels, 
the panels themselves can become high-energy missiles that can damage buildings and other 
property (Figure 5-18). Metal panels contributed significantly to the amount of debris from 
Hurricane Georges. 
Many roofs were corroded because their galvanized coating was not very resistant to 
corrosion. Many were also not field painted. Use of an aluminum-zinc alloy coating 
(Galvalume) greatly enhances corrosion protection and is particularly beneficial for roofs 
located near salt water. 
5.3.2 Exposed Concrete and Liquid-Applied Membranes Over Concrete 
The BPAT observed several cast-in-place concrete roofs with no roof covering. While these 
roofs provided excellent wind performance, some leaked during the hurricane due to the 
heavy rains that accompanied the storm (Figure 5-19). Roofs with liquid-applied membranes 
over the concrete provided excellent performance. 
FIGURE 5-18 Corrugated 
metal panel wrapped around a 
power pole.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-15 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-19 This concrete roof deck did not have a roof covering. During the 
hurricane, water entered the house through the deck. The concrete deck and 
CMU walls were skimmed with a skim coat of plaster. This house has 
Miami windows. 
FIGURE 5-20 These tiles were heavily damaged, although the wind speed at this 
location was not very high. As can be seen in the foreground, the roof covering 
generated a substantial number of missiles. Because of the relatively low wind 
speed, the tile debris did not travel very far. 
5.3.3 Tile 
While the BPAT observed clay and concrete tile roofs, they make up only a small percentage of 
steep-slope roofs in Puerto Rico. The BPAT observed many damaged tile roof coverings (Figure 5- 
20). In some cases, uplift pressure initiated failure while in others it was caused by missile impact.
5-16 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
Concrete and clay tile roof coverings were vulnerable to missiles. Even when their attachment 
was well designed and tiles were properly installed, their brittle nature made them especially 
susceptible to relatively low-energy missiles. Debris from a single damaged tile can impact other 
roof tiles and lead to a progressive cascading failure. In addition to the roof damage, many highenergy 
missiles can became airborne. 
5.3.4 Liquid-Applied Membranes Over Plywood 
The BPAT observed only a few liquid-applied membranes over plywood. As long as the roof 
structure did not fail they provided excellent wind performance (Figure 5-21). 
FIGURE 5-21 This house had a liquid-applied membrane over plywood roof 
sheathing. This type of roof system typically offered excellent wind performance 
provided the plywood does not lift. This house was located on the island of 
Culebra. 
5.3.5 Built-Up Membranes 
Several built-up roofs experienced membrane lifting and peeling. Since these roofs were not 
generally exposed to very high winds, damage usually was limited to corner areas, rather than 
complete loss of the roof covering (Figure 5-22). 
In at least one instance, aggregate (gravel) from an aggregate surface built-up roof broke a 
large number of windows down wind (Figure 5-23). As demonstrated again in this hurricane, 
aggregate from built-up membranes can travel a substantial distance and break glass. On some 
buildings, tall parapets have been installed to mitigate this type of damage. However, 
presently there is insufficient guidance available on required parapet height with respect to 
design wind speed. The double surfacing technique, wherein essentially all of the aggregate is 
embedded in bitumen, has proven to be a successful means of preventing aggregate blow-off. 
However, this is a relatively expensive technique. The most conservative approach to this 
problem is to eliminate the use of aggregate surfacing, but a mineral surface cap sheet, fieldapplied 
coating, or an alternative type of roofing system can also be used.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-17 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-23 The windows in this building were broken by aggregate from the 
built-up roof of a nearby building (Figures 5-24 and 5-25). 
FIGURE 5-22 This built-up membrane had a mineral surface cap sheet. Because 
of the roof covering damage, this manufacturing facility on the island of Culebra 
was shut down for approximately two weeks after the hurricane. This building also 
experienced roof damage during Hurricane Hugo in 1989.
5-18 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
5.3.6 Sprayed Polyurethane Foam 
Several sprayed polyurethane foam roofs were observed. They provided excellent wind 
performance provided the substrate did not lift. Many of them, however, needed to be 
recoated even before Hurricane Georges occurred. (Recoating is related to long-term roof 
system performance rather than wind resistance.) 
5.3.7 Other Roof Coverings 
The BPAT observed several other types of roof coverings, including asphalt roll roofing, 
corrugated asphaltic panels, and asphalt shingles. Since Puerto Rico has so few of these types 
of roof coverings, detailed observations were not conducted. The performance of asphalt roll 
roofing and shingles varied. 
5.4 Windows, Shutters, and Skylights 
Several types of window, shutter, and skylight problems were observed with residential 
and commercial buildings. Some problems were caused by missiles and others by overpressurization. 
Most houses had Miami windows, which are metal jalousie louvers, as shown in Figures 
5-16 and 5-19. Since there is no glass in the opening, very high or low internal air pressure 
can be induced, depending upon wind direction and location of other openings in the 
building. In addition, these units do not offer much protection against wind-driven rain. 
Window and door failure effects are discussed in Section 5.1. Windows are more of a 
problem than non-glazed doors because they are more susceptible to missile damage. While 
the probability that any one window will be struck by a missile is small, when it does occur, 
the consequences can be significant. The probability of missile impact depends upon local 
wind characteristics and the number of natural and man-made windborne missiles in 
the vicinity. 
Windows can be protected from missile damage by special glazing or exterior shutters. 
Previous research and testing has shown that if special glazing is used, laminated rather than 
tempered glass should be specified. Although laminated glass is more easily broken than 
tempered glass, there is a greater probability that broken laminated glass will stay in the frame 
(provided the frame detailing is suitable); tempered glass will shatter and fall out of the frame 
as illustrated by Figures 5-24 and 5-32. 
Although shutters are intended to protect glazing from missile impact, most shutter 
designs do not substantially reduce the wind pressure that is applied to the glazing. 
Accordingly, glazing protected by shutters should be designed to resist the full positive and 
negative design wind loads. 
Glazing is not typically used with Miami window systems. Therefore, wind loading on 
buildings with Miami windows should be determined by using ASCE 7-95. This typically 
results in the building being assessed as partially enclosed (i.e., design for high internal 
air pressure).
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-19 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-25 Although some annealed panes broke into shards, others just 
broke at the impact point. 
FIGURE 5-24 When these tempered panes broke, they did not produce shards 
of glass, as did the annealed panes. 
5.4.1 Windows 
The building in Figure 5-23 had approximately 100 windows broken by aggregate that blew 
off of a built-up membrane roof across the street. Some panes were tempered glass (Figure 5-24) 
and others were annealed (Figure 5-25).
5-20 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-27 One pane in this window was broken by a missile, perhaps from 
the palm in the foreground. 
FIGURE 5-26 Half of the window frame blew out. It was attached with two 
screws in plastic sleeves at the head, three screws at the jamb, and two screws 
at the sill. 
The window frame in Figure 5-26 was blown out by over-pressurization of the building 
interior when the building envelope was breached elsewhere in the building. Missiles broke 
the glass shown in Figures 5-27 and 5-28. The three buildings in these photos are all located 
near one another.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-21 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-28 This large window, which was removed and leaned against the wall 
after the storm, was broken by a missile, most likely a tree limb. 
FIGURE 5-29 The glass and frames were blown out at the center room on the 
top floor. At the room to the right, one of the glass panes was blown out. 
In Figure 5-29, some window frames in this mid-rise building were blown out while in other 
cases, just the glass was blown out. This appeared to be caused by negative pressure (suction).
5-22 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-31 High-energy missiles from a nearby building damaged several 
railings of this building. 
FIGURE 5-30 Several window 
and glass door openings broke 
during the hurricane. They were 
subsequently covered with 
plywood (Figure 5-31). 
The building in Figures 5-30 and 5-31 experienced substantial damage to windows and 
sliding glass doors. Missiles caused at least part of this damage. The window in Figure 5-32 
broke, but since the glass was laminated it did not fragment into separate pieces.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-23 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-32 The broken 
light in the center is 
laminated. A sliding glass 
door located to the left had 
tempered glass, which was 
blown out of the frame. 
5.4.2 Shutters 
Many residential and commercial buildings were equipped with shutters of various designs 
and materials, as shown in Figures 5-33 through 5-39. Problems observed included shutter panel 
loss, shutter panel displacement (i.e., the panel deflected and pressed against the window), 
shutter track loss, and blow-out of the window to which the shutter was attached (Figure 5-40). It 
should be noted that Miami windows look like a type of storm shutter, but offer very little missile 
protection.
5-24 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-33 A combination of boards and metal panel was used to construct 
this shutter. Unless shutters are well attached, they can blow off during high 
winds and become missiles themselves. 
FIGURE 5-34 These windows were equipped with permanent head and sill 
shutter tracks, which were attached to the wall with closely-spaced fasteners 
(Figure 5-35).
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-25 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-36 Looking up at a shutter panel held in place by clips (a metal wall 
panel occurs below the shutter track). These clips were spaced 12-in on center. 
Clips are not as reliable as the bolted attachment shown in Figure 5-35. 
FIGURE 5-35 Close-up of Figure 5-34. The steel shutter panels were designed to 
be locked into the track with wing nuts spaced 6-in on center, a more reliable 
attachment than that shown in Figure 5-36.
5-26 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-37 These windows were equipped with roll-up shutters. 
FIGURE 5-38 This house had hinged plywood shutters. The front shutter 
protects a Miami window.
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-27 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-39 Steel shutters were used on this mid-rise building, which had a 
narrow balcony in front of the windows. Since wind speed increases with building 
height, the shutters on the upper floors can receive very high wind loads. The 
length of the shutters on this building requires the shutter panels and their 
connection to the tracks to be strong enough to resist being blown out of the 
track. The shutter panels also must be stiff enough to prevent deformation 
against the glass, or they must be set far enough away from the glass so they do 
not press against it. 
FIGURE 5-40 The window lying on the ground was protected by a shutter. 
However, the shutter was attached to the window frame. The window frame 
fasteners were over-stressed and the entire assembly failed. Attachment of the 
shutter directly to the wall framing is a more reliable method of attachment.
5-28 Building Performance Assessment: Hurricane Georges In Puerto Rico 
BUILDING ENVELOPE PERFORMANCE Section 5 
FIGURE 5-41 Part of the exterior envelope of this building blew away, resulting 
in damage to the acoustical ceiling. This revealed a lack of seismic resistance of 
the ceiling system, light fixtures, and ductwork. 
5.4.3 Skylights 
The BPAT observed a few broken skylights during its investigation. Most were glazed with 
acrylic sheet. Missiles caused some of the damage. In a large atrium covered with 
prefabricated translucent panels, many of the skylight panels were blown off. 
5.5 Seismic Resistance of Nonstructural Elements 
The BPAT noted the lack of compression struts, diagonal ties, and perimeter suspension 
wires in several buildings with acoustical ceilings (Figure 5-41). A lack of bracing was observed 
on some interior gypsum board/stud partitions as well as inadequate reinforcement and 
bracing of interior non-load bearing CMU walls (Figure 5-42).
Building Performance Assessment: Hurricane Georges In Puerto Rico 5-29 
Section 5 BUILDING ENVELOPE PERFORMANCE 
FIGURE 5-42 An interior view of a house under construction (the steel joists are 
supporting formwork for the concrete slab). The CMU partition is inadequately 
reinforced and is not supported or laterally braced at the top of the wall.
Building Performance Assessment: Hurricane Georges In Puerto Rico 6-1 
Section 6 EXTERIOR MECHANICAL AND ELECTRICAL EQUIPMENT 
6 Exterior Mechanical and Electrical Equipment 
Hurricane Georges caused few problems to Puerto Rico.s exterior-mounted mechanical 
and electrical equipment. The most commonly observed problem was blow-off of exhaust fan 
cowlings, as shown in Figure 6-1. Many residences and other buildings have water storage 
tanks on their roofs and most appeared to have performed well. However, as documented in 
Section 5.2.1, one tank blew off and damaged a hospital. Solar hot water heaters are located 
on many buildings and they also performed well. One solar heater that did not is shown in 
Figure 6-2. 
FIGURE 6-1 This exhaust fan lost its cowling.
6-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
EXTERIOR MECHANICAL AND ELECTRICAL EQUIPMENT Section 6 
FIGURE 6-2 This roof had several solar hot water heaters that successfully 
weathered Hurricane Georges. However, the unit in the foreground was 
damaged. 
FIGURE 6-3 Flood water entered this generator room and reached a height of 
about 2 feet, as indicated by the red line. This facility is located in Jayuya. 
During Hurricane Georges, an emergency generator at a water treatment plant was 
flooded by a nearby river, rendering the generator unusable. As shown in Figure 6-3, the 
water rose approximately 2 feet above the generator room floor.
Building Performance Assessment: Hurricane Georges In Puerto Rico 6-3 
Section 6 EXTERIOR MECHANICAL AND ELECTRICAL EQUIPMENT 
FIGURE 6-4 This service mast is mounted on a concrete pylon. This form of 
service connection was successful in eliminating roof damage when the overhead 
service blew down. 
Several residences in Puerto Rico have overhead electrical service to a service mast 
mounted on a free-standing concrete pylon. From the service mast to the building, the 
service was underground, as shown in Figure 6-4. The advantage of this type of service mast 
versus one mounted through the roof is that if the mast deflects or is torn away, the roof is 
not damaged.
Building Performance Assessment: Hurricane Georges In Puerto Rico 7-1 
Section 7 ELECTRICAL DISTRIBUTION SYSTEM 
7 Electrical Distribution System 
The electrical distribution system in Puerto Rico, which is installed on wood or concrete 
poles, was severely damaged by Hurricane Georges. The loss of electrical service to water 
treatment plants resulted in widespread disruption of the delivery of water, which directly 
affected people.s personal lives. Loss of electrical service also resulted in major economic 
disruption and significantly increased disaster response needs. 
Damage of the distribution and in the transmission systems fell into the following areas: 
n Broken wood poles: This was caused by too great a load on the pole, including 
too large a span or various heavy communication lines on the poles (Figures 7-1 
and 7-4). 
n Leaning poles (wooden and concrete): This was considered minor damage and 
was easily corrected by straightening and properly embedding the poles in the 
ground (Figure 7-2). 
n Broken concrete poles: Round spun concrete poles generally perform better than 
the reinforced concrete poles that are widely used in Puerto Rico. There was 
evidence of spalling and cracking of reinforced concrete poles indicating a 
probable quality control problem (Figure 7-3). 
n Fallen poles: This was a result of improper embedment. Additional damage 
occurred to the conductors, causing progressive failure to other poles.
7-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
ELECTRICAL DISTRIBUTION SYSTEM Section 7 
FIGURE 7-2 Leaning wood pole 
due to inadequate embedment. 
FIGURE 7-1 Damaged wood pole. The portion of the wood pole in the 
foreground broke from the pole (circled) in the back of the picture.
Building Performance Assessment: Hurricane Georges In Puerto Rico 7-3 
Section 7 ELECTRICAL DISTRIBUTION SYSTEM 
FIGURE 7-3 Observed crack in concrete pole that appears to be a quality 
control problem. 
FIGURE 7-4 New wood 
pole replaced after the 
hurricane; utility lines are 
still being attached to the 
pole. Inset shows wood 
pole grade marking. This 
#3 pole was typical of 
those used throughout 
the island.
Building Performance Assessment: Hurricane Georges In Puerto Rico 8-1 
Section 8 CONCLUSIONS 
8 Conclusions 
The conclusions of this report are intended to assist the Government of Puerto Rico in 
shaping its post-Hurricane Georges construction strategy and assist designers, contractors, 
and building owners in the construction of hazard-resistant buildings. These conclusions are 
based solely on the BPAT.s observations, an evaluation of relevant codes and regulations, and 
meetings with the Government of Puerto Rico. 
8.1 General Conclusions 
Hurricane Georges was a strong Category 2 hurricane when it hit Puerto Rico. The 
successful performance of buildings in more severe events should not be assumed based 
upon the lack of damage observed from Hurricane Georges. 
A large number of residential buildings in Puerto Rico experienced structural damage 
from the high winds of Hurricane Georges. In addition, a large number of residential 
buildings in SFHAs were damaged from floodwaters. The BPAT did not identify the history of 
these buildings and how they were permitted, designed, or constructed. However, the BPAT 
understands that housing is often built by owners without a building permit or design 
services. When the BPAT observed improper construction practices or siting, the houses 
were described as self-built. These self-built houses received the majority of damage observed 
from Hurricane Georges. The severe damage to these self-built houses could have been 
avoided if more buildings had been constructed to existing Planning Regulation 7 (building 
code) and Planning Regulation 13 (floodplain management). 
The BPAT observed a large number of .concrete. houses constructed with a structural 
system consisting of walls with a concrete frame, masonry infill, and a concrete roof deck as 
described in Section 3.4.1. The first floors of these houses were often supported on long, 
slender concrete or masonry columns, which pose a significant collapse hazard if the island 
experiences a major earthquake. 
A limited number of mid- and high-rise buildings were inspected by the BPAT. The 
damage observed at these buildings was to nonstructural elements, including damage to 
glazing, curtain walls, interior walls, and damages to finishes from windborne rain. Some 
building owners reported that they expected to lose the use of their buildings for repair 
periods of up to two months, resulting in significant business losses. Building envelope 
damage resulted from loads on the components and windborne debris that broke glazing. 
Future damage can be reduced if components and cladding are designed and constructed to 
the newly adopted 1997 UBC and wind provisions of ASCE 7-95.
8-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
CONCLUSIONS Section 8 
ARPE has proceeded with several important actions following Hurricane Georges in an 
effort to increase public safety and reduce property damage from future natural hazards. 
These actions include: 
n At the request of ARPE, the International Conference of Building Officials (ICBO) 
conducted and completed a peer review of ARPE in January 1999. This peer 
review evaluated the new needs created by Hurricane Georges as well as the reengineering 
effort currently underway. 
n Revised planning regulations based on the 1997 UBC were adopted as emergency 
regulations in December 1998. 
n ARPE is positioned to make recommendations concerning building regulations to 
the new Certification and Building Board of Puerto Rico that is expected to be 
created in March 1999 under proposed legislation submitted by the Governor to 
the Puerto Rico Legislature. 
n ARPE and FEMA are implementing a strategic plan to provide the necessary 
training to make the transition to these new building regulations. 
8.1.1 Mitigation Efforts 
Effective mitigation measures reduced the demands on the response and recovery stages 
following Hurricane Georges. More importantly, however, effective efforts diminished the 
stress on the lives of inhabitants and the occupants of buildings during and after the storm. 
The most prevalent and successful mitigation measure the BPAT observed was the use of 
concrete and masonry for the construction of the exterior walls and roof. Reinforced 
concrete and masonry envelopes almost without exception provided excellent resistance to 
wind forces and windblown debris. They were also extremely reliable and durable, as 
illustrated in Figure 8-1. 
FIGURE 8-1 The three concrete/masonry buildings in this photo appeared to be 
undamaged. However, the building with the wood-frame roof structure 
experienced significant damage. 
Damaged building with woodframe 
roof structure 
Damaged building with woodframe 
roof structure 
Concrete 
buildings 
Concrete 
buildings
Building Performance Assessment: Hurricane Georges In Puerto Rico 8-3 
Section 8 CONCLUSIONS 
FIGURE 8-2 This wood-framed house was nearly totally destroyed. This is in 
remarkable contrast to the nearby building shown in Figure 8-3. 
FIGURE 8-3 This wood-framed house is close to the house shown in Figure 8-2. 
The wind flow was essentially identical at these two sites, hence the successful 
performance of the one building is attributable to the attention given to design 
and construction. The value of mitigation is clearly illustrated in these two starkly 
different cases. 
Although the BPAT observed many wood-frame building failures, as illustrated in Figure 
8-2, wood-frame buildings perform well in high winds if effective mitigation measures are 
taken during design and construction. This is illustrated in Figure 8-3.
8-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
CONCLUSIONS Section 8 
Effective mitigation considers the structural and nonstructural aspects of a building. If the 
building structure is designed for the wind loads and remains undamaged, large losses can 
still occur to the building interior and its contents from damage to windows, siding, or the 
roof covering (the building envelope as discussed in Section 5). Exterior-mounted 
mechanical and electrical equipment are also susceptible to flood and wind damage and must 
be protected, as discussed in Section 6. 
Effective mitigation also considers the natural hazard risks to the building. For example, if 
concrete houses are built for wind-resistance, but elevated on long, slender columns, they 
pose a threat of collapse during a major earthquake. If effective mitigation measures had been 
implemented more extensively in the design and construction of buildings, the widespread 
devastation of Hurricane Georges would have been substantially reduced. 
8.1.2 Wind Mitigation for Existing Buildings 
The BPAT inspected a few older residences that had been retrofitted prior to Hurricane 
Georges. The BPAT found that the mitigation measures that were taken were not as effective 
as they could have been. The most common mitigation measure observed was the installation 
of metal framing connectors between rafters and bearing walls (Figure 4-12). However, in 
each of the observed buildings, the mitigation effort did not address the weak connections of 
the metal roof panels to the wood nailers, or the weak connections between the nailers and 
rafters. Hence, only part of the load path between the roof covering and the foundation was 
strengthened. Because the attachment of the roof covering system was not upgraded along 
with other mitigation efforts, most of the houses inspected experienced significant roof 
covering damage and subsequent damage to their interior and contents. The BPAT 
concluded that mitigation measures would have been more successful if they were part of an 
overall mitigation plan and if each measure had been completely, rather than partially, 
carried out. 
When existing building are to be strengthened, mitigation efforts are planned, ranked, 
and executed so that the most vulnerable parts of a building are addressed first. For example, 
if a complete load-path retrofit is not possible then strengthening the roof covering is 
accomplished first. Since a weak roof covering typically fails at lower wind speeds than the 
rest of the structure.and the failure of the roof covering usually results in interior damage 
from rain.strengthening the roof covering will reduce future losses in weaker hurricanes. 
After mitigation efforts have been prioritized, they must be executed correctly and 
completely. For example, if additional metal roof panel fasteners or metal framing connectors 
are necessary, the fasteners must be the correct type, size, and spacing and used over the 
entire roof to achieve maximum effectiveness from the mitigation effort. 
8.2 Planning Regulations in Puerto Rico 
The following subsections discuss the BPAT.s conclusions regarding the planning 
regulations in Puerto Rico governing the design and construction of buildings that were in 
effect when Hurricane Georges occurred. Regulations are organized into three groups: wind, 
seismic, and floodplain management provisions. 
Planning Regulation 7 of Puerto Rico, which was in effect at the time Hurricane Georges 
struck, was originally adopted in 1968 and amended in 1987. The seismic and wind load 
provisions of the 1987 amendment are based on the 1982 UBC. The materials chapters 
reference national standards such as ACI for concrete (ACI-318-83) and masonry (ACI-531- 
79), and AISC (AISC-78) for steel construction, with amendments for seismic design. By
Building Performance Assessment: Hurricane Georges In Puerto Rico 8-5 
Section 8 CONCLUSIONS 
comparison, the newly adopted 1997 UBC (which now serves as the building code) references 
updated national standards such as ACI-318-95 for concrete and AISC-LRFD-93 and AISC-ASD-89 
for steel construction, both with amendments for seismic design. 
8.2.1 Wind Provisions of Planning Regulation 7 
A substantial amount of wind engineering research has been completed since Planning 
Regulation 7 was amended in 1987. As a result, Puerto Rico.s wind load provisions were out 
of date during Hurricane Georges. Of particular concern were the lack of consideration for 
wind speedup due to abrupt changes in topography and the low loads prescribed for 
residential windows, doors, and roofs. 
The BPAT observed that many failures occurred on buildings that did not comply with 
Planning Regulation 7. Most of these failures likely could have been avoided if the buildings had 
complied with the code. However, in many cases, Planning Regulation 7 criteria significantly 
under-predicted loads, which can result in failure even for code-complying buildings. For 
buildings to perform well during high-wind events, and remain economical, their wind 
design must be based upon current criteria derived from ongoing wind engineering 
research, including post-disaster forensic engineering investigations. 
In response to the BPAT.s conclusions, an emergency regulation to repeal Planning 
Regulation 7 and adopt the 1997 UBC as the building code for Puerto Rico was implemented 
by the Governor of Puerto Rico and approved by the Planning Board in December 1998. The 
1997 UBC, with specified amendments that include the use of ASCE 7-95 for determining 
design wind loads, addresses most of the wind provision deficiencies that existed under 
Planning Regulation 7. The deficiencies that were not addressed are covered in Section 9. 
8.2.2 Seismic Provisions of Planning Regulation 7 
Planning Regulation 7 was also out of date with regard to seismic design provisions. It 
referenced standards that were nearly 20 years old. Significant improvements in seismic 
design provisions have taken place as a result of engineering research and lessons learned 
from recent earthquakes. 
The Government of the United States is attempting to improve the seismic safety of 
federally owned, leased, assisted or regulated buildings through compliance with Executive 
Order 12699: Seismic Safety of Federal and Federally Assisted or Regulated New Building 
Construction. EO12699 was signed in 1990 and seeks to ensure that federally owned, leased, 
assisted or regulated new building construction is designed and constructed in accordance 
with appropriate state-of-the-art seismic design standards. The Executive Order requires use 
of seismic design standards .substantially equivalent. to the most recent or immediately 
preceding versions of the NEHRP Recommended Provisions. 
Since NEHRP Provisions define Puerto Rico.s location as a high seismic zone, EO 12699 
also includes residential and commercial buildings that receive federal assistance. Therefore, 
to comply with EO12699, codes substantially equivalent to the 1997 NEHRP Provisions must 
be used in the design, construction, and inspection of new buildings where Federal financial 
assistance is used. Currently, the 1997 Uniform Building Code (UBC) meets this requirement. 
Puerto Rico.s Planning Regulation 7 was not .substantially equivalent. as defined by 
EO12699. As such, any new construction that receives federal funds must exceed the 
requirements of the 1987 amendment to Planning Regulation 7. In response to these issues, 
Puerto Rico repealed Planning Regulation 7 and adopted the 1997 UBC as the building code for
8-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
CONCLUSIONS Section 8 
Puerto Rico. Through the CIAPR, Puerto Rico has developed a well-conceived plan for earthquake 
recording instrumentation. Therefore, this existing plan for earthquake recording instrumentation 
remains in place in lieu of the 1997 UBC seismic instrumentation provisions. 
8.2.3 Floodplain Management Provisions of Planning Regulation 13 
In August 1978, the Government of Puerto Rico entered into the NFIP, which was created to 
make affordable flood insurance available to property owners in communities agreeing to enact 
and administer floodplain management regulations that meet minimum NFIP program 
requirements. The Government of Puerto Rico adopted these provisions as Planning 
Regulation 13 and they are now regulated by the Puerto Rico Planning Board and ARPE. 
Therefore, since 1978, new and substantially improved buildings in SFHAs in Puerto Rico 
must be built in such a manner as to reduce flood hazards. 
The Government of the United States has also implemented Executive Order 11988: 
Floodplain Management in an effort to update design and construction practices for federal 
buildings. EO11988 requires federal agencies to undertake sound floodplain management 
practices when spending federal funds or making regulatory or policy decisions. These 
requirements must also be considered in the delivery of federal disaster assistance. 
The BPAT concluded that Planning Regulation 13, along with EO11988, gives the Puerto 
Rico Planning Board and ARPE the ability to permit, oversee, and regulate construction in 
SFHAs to minimize the risk of property loss from severe flood events. However, the Planning 
Board and ARPE will continue to experience difficulties in both the disaster and non-disaster 
environment with unauthorized and un-permitted construction that is common in 
the SFHAs. 
8.3 Regulatory Administration and Enforcement 
The ICBO.s peer review of ARPE assessed its efforts to administer and enforce planning 
regulations related to building design and construction. The review evaluated ARPE.s current 
needs.and identified unmet needs.to respond effectively to the massive amount of 
reconstruction necessary following Hurricane Georges and new construction in the future. 
The peer review resulted in recommendations in the areas of policies, procedures, practices, 
training and education, facilities, salary, benefits, promotion, and office automation. Since the 
completion of the peer review, FEMA, ICBO, and ARPE have been working closely together to 
develop a plan that meets the identified unmet needs. Both short- and long-term needs will 
be addressed in this plan. 
The BPAT.s limited investigation of current building construction practices, construction 
permitting, and enforcement of the building regulations identified unregulated and illegal 
construction, provisions in existing statutes, regulations, policies, and practices that allow for 
unregulated construction and improvements of residential buildings. The BPAT concluded 
that the extensive damage observed in residential construction from Hurricane Georges was 
due to a lack of enforcement of Planning Regulation 7. 
According to the regulations, all construction projects in Puerto Rico require 
construction and use permits. Although the value of a project dictates the amount of 
documentation that must be submitted, many buildings have been constructed without any 
permits. Loopholes in the regulations and a lack of enforcement of the permitting 
regulations have led to the construction of additional unregulated, insufficiently designed 
and constructed buildings. In addition, conflicts between the permitting process in Puerto
Building Performance Assessment: Hurricane Georges In Puerto Rico 8-7 
Section 8 CONCLUSIONS 
Rico and the NFIP have not been addressed and have lead to the construction of buildings that 
were legally constructed from a permitting perspective, but are non-compliant with the NFIP and 
Planning Regulation 13. 
ARPE faces difficult challenges in both the disaster and the non-disaster environment with unpermitted 
floodplain construction. Un-permitted floodplain development was previously 
observed in the May 1998 CAV conducted by FEMA.s New York and Caribbean Regional 
Offices. The CAV found that many floodplain structures in Puerto Rico were at risk from 
flooding because they had been either built in violation of Planning Regulation 13 or 
subsequently altered without permits. Flooding associated with Hurricane Georges made 
that risk a reality and, consequently, many structures suffered significant.and 
unnecessary.damage. 
8.4 Training and Continuing Education 
As described in Section 8.3, the ICBO peer review of ARPE included recommendations 
on training and education needs. Unmet training needs were identified for ARPE staff, design 
professionals, technicians, builders and contractors, the banking and mortgage industries, the 
insurance industry, and public policy decision makers. As part of the peer review process, 
ARPE and FEMA developed a comprehensive plan to provide the necessary training to each 
of these groups with the goal of ensuring that the transition to a new building code 
progressed smoothly and that the post-Hurricane Georges reconstruction process was not 
interrupted. 
8.4.1 Government of Puerto Rico Personnel 
New residential construction activity in Puerto Rico is expected to increase dramatically 
during the next few years as severely damaged or destroyed housing is replaced. ARPE is 
currently determining the additional resources that will be required for space, management, 
and, most importantly, trained personnel. ARPE may be able to bring on trained code 
personnel to help them immediately, but as a long-term solution, ARPE must consider hiring 
and training additional staff. 
8.4.2 Design Professionals and Building Contractors 
Continuing education for design professionals and contractors is an effective vehicle for 
improving building regulation compliance. Under the comprehensive training plan, a variety 
of sources are being mobilized to provide training in building regulations and construction 
practices, including local engineering/architectural groups, professional engineering 
societies, model code organizations, the academic community, and building trade 
associations. The ability to develop this professional training is enhanced by the strong 
presence of Puerto Rico.s academic and professional societies. 
8.5 Structural 
Structural building elements that were not designed or engineered to Planning Regulation 7 
requirements of 110 mph (fastest-mile) design winds resulted in many residential structure 
failures. The BPAT observed buildings apparently designed to this standard that survived 
Hurricane Georges with no structural damage. However, as previously stated, this hurricane was 
not a design wind event for the island and the buildings constructed to Planning Regulation 7 are 
still considered vulnerable to forces from future wind, flood, and seismic events. The recent 
adoption of the 1997 UBC and the ASCE 7-95 wind provisions will help to improve the structural 
performance of buildings in Puerto Rico.
8-8 Building Performance Assessment: Hurricane Georges In Puerto Rico 
CONCLUSIONS Section 8 
The non-engineered, self-built homes the BPAT observed performed poorly during the 
hurricane due to a lack of a continuous load path from the roof system to the foundation. A 
lack of compliance and enforcement of Planning Regulation 7 has resulted in a large number 
of buildings incapable of carrying the prescribed load. Marginally engineered buildings 
constructed from materials capable of withstanding design loads, reinforced concrete and 
masonry, performed well and did not experience significant structural damage. In instances 
where concrete and masonry construction combined with wood construction in the same 
building, the wood structures often failed while the concrete and masonry structures did not. 
Fully engineered buildings, the larger commercial buildings, constructed of steel and 
reinforced concrete and masonry, performed well and generally did not experience 
structural damage. 
8.5.1 Structural Seismic Conclusions 
Based upon discussions with ARPE, the BPAT understands that permitted buildings must 
be designed by engineers or architects. In addition, design professionals in Puerto Rico carry 
additional responsibilities for inspection of construction that, in areas outside Puerto Rico, 
are normally the responsibility of the building department. For this reason, the mid- and 
high-rise buildings the BPAT inspected were assumed to be professionally designed by 
engineers and architects and met the minimum structural seismic regulations in effect at the 
time of the building design. For more recently constructed buildings, this assumed they were 
in compliance with the seismic provisions of the 1987 amendments to Planning Regulation 7. 
Most residential buildings (specifically, single-family homes) were not observed to be in 
compliance with current codes and regulations. Many of these residential buildings are 
susceptible to damage from seismic events of even less than the design event specified in 
Planning Regulation 7. Foundation systems comprised primarily of tall, slender columns with 
no intermediate bracing and shear wall systems that support the building in only one lateral 
direction were common on the island. 
8.6 Architectural 
The failure to design and/or test architectural components for the wind load prescribed 
in Planning Regulation 7 was the primary cause of building envelope problems from 
Hurricane Georges. However, some of the building envelope failures were likely due to 
inadequacies in the wind load provisions in Planning Regulation 7, particularly for one- and 
two-family houses. For these houses, Planning Regulation 7 prescribes a load of 36 psf for 
doors and windows, and 60 psf for roof edges. In comparison, using ASCE 7-95, the load on 
doors and windows varies between 54 psf and 81 psf, depending upon exposure and location 
of the opening (i.e., near a corner or away from the corner). For a moderately-sloped roof 
with an overhang, using ASCE 7-95.depending upon the exposure.the load on the roof 
covering varies between 134 psf and 164 psf at the corners, and 88 psf to 110 psf at the eaves, 
rakes, and ridges (assuming the house has Miami windows). The recent adoption of the 1997 
UBC, along with the ASCE 7-95 wind provisions, will address these concerns. 
The amount of damage that water infiltration caused was reduced because of the primary 
construction materials used. The most notable examples were found in flooring and walls. In 
place of carpet, concrete or vinyl was typically found in houses; instead of gypsum board, the 
walls were generally masonry. Cleanup and minor cosmetic repairs were still necessary, but costly 
removal and replacement of water-susceptible materials was avoided.
Building Performance Assessment: Hurricane Georges In Puerto Rico 8-9 
Section 8 CONCLUSIONS 
8.6.1 Doors 
Some of the poor door performances the BPAT observed were due to inadequate design or 
application of the attachment of the door frame to the wall. These vital connections are often 
overlooked by designers and not given sufficient consideration by contractors. Several glass doors 
were damaged by missile impact. To avoid impact damage, glass doors must be protected with 
shutters or glazed with impact-resistant glazing (i.e., laminated glass). 
Security grilles were observed to offer good wind performance. They offer greater windresistance 
reliability than rolling or garage doors because of the large amount of net free 
open area. 
8.6.2 Walls 
The BPAT observed several problems with stucco blown from concrete. This could have 
been avoided by improving the workmanship of the concrete surface and leaving it exposed 
or having it painted. Poor performance of exterior metal wall coverings was primarily 
attributed to failure to test and/or adequately design wall assemblies for the wind load. Poor 
EIFS performance was related to workmanship in at least one instance. In another case, it was 
related to workmanship or failure to test and/or design the wall assembly for the wind load 
prescribed in Planning Regulation 7. 
8.6.3 Roof Coverings 
Liquid-applied roof coverings over concrete decks and plywood decks provided excellent 
wind performance. Sprayed polyurethane foam roofs also performed well. This system, 
however, was not commonly used and many of these roofs required recoating. 
The BPAT found that corrugated metal roof coverings generally were attached 
insufficiently. This is the prevailing roof covering in Puerto Rico, and it experienced the 
greatest number of failures. In many cases, the plane of failure was between the metal panels 
and the wood nailers, while in others it was between the nailers and joists/trusses or between 
the joists/trusses and bearing walls. Several roofs were very corroded. 
Many exposed concrete roofs leaked during the hurricane. Unless protected with a roof 
covering, these decks could eventually experience problems with corrosion of the slab 
reinforcement. 
As demonstrated in other hurricanes, and again demonstrated by Hurricane Georges, 
aggregate from built-up roofs can be picked up by hurricane winds and cause significant glass 
damage, both to the building with the aggregate roof surfacing as well as nearby buildings. 
Several built-up membrane roofs experienced partial membrane blow-off. Inadequate 
attachment of the metal edge flashing/coping was the likely source of these problems. 
Although roof tiles are not in widespread use, the BPAT observed that roof tile performance 
was typically poor. 
8.6.4 Glazing 
Broken glazing was the most common type of damage in low-, mid-, and high-rise 
buildings. Some glazing was lost due to over-pressurization while windborne debris (missiles) 
caused other glazing to break. Over-pressurization problems were primarily attributed to 
failure to test and/or adequately design assemblies for the wind load. Missile impact problems 
were primarily attributable to lack of missile criteria in Planning Regulation 7.
8-10 Building Performance Assessment: Hurricane Georges In Puerto Rico 
CONCLUSIONS Section 8 
8.6.5 Shutter Systems and Impact-Resistant Glazing 
Shutter systems were placed over windows on many buildings prior to the hurricane. Many of 
these systems appeared to offer sufficient resistance to missiles and wind pressures. However, in 
numerous cases observed, shutter systems afforded limited resistance to missiles and many were 
susceptible to blow-off. Some shutters had the potential to deform and break the glass they were 
intended to protect. Furthermore, Miami windows are not very resistant to wind-driven water or 
high energy missiles and they should not be considered to be storm shutters. 
In one instance, the BPAT observed a room, which had been used as a shelter, that was fully 
glazed on three sides and protected by shutters. Because of a concern of failure during Hurricane 
Georges, as indicated by excessive deflection and vibration, occupants were sent to other areas of 
the building during the storm. Areas used as shelters must be specifically designed for this very 
purpose and contain only small areas of fully protected glazing. 
The BPAT observed only one example of impact-resistant glazing (i.e., laminated glass). 
Although the glass broke, it remained in the frame as intended. 
8.6.6 Weatherstripping 
The BPAT concluded that greater attention must be paid to weatherstripping doors and 
windows and the water resistance of the joints between walls and door and window frames. 
This was not a major issue during Hurricane Georges because it was overshadowed by the 
poor performance of the building envelope or structure. However, unless this type of water 
leakage is addressed, water damage will occur even on buildings with envelopes and 
structures that perform well otherwise. Although the amount of water that can enter around 
doors and walls is minor compared to the amount that can enter through breached windows 
or roofs, a sufficient amount of water can enter and cause notable damage. 
8.6.7 Seismic Resistance of Nonstructural Elements 
The BPAT concluded that the design of seismic resistance of nonstructural elements in 
Puerto Rico, including ceilings, non-load bearing exterior walls, and non-load bearing interior 
partitions often receive insufficient attention. Where suspended ceiling tile was removed 
because of water or wind damage, the BPAT observed that nonstructural elements were not 
connected to structural members with seismic resistant connectors. 
8.7 Exterior Mechanical and Electrical Equipment 
Greater attention to the attachment of rooftop equipment is also required. Cowlings on 
exhaust fans were susceptible to blow-off. On-site strengthening is necessary unless 
equipment manufacturers respond with units of adequate strength. 
For buildings located in floodprone areas, mechanical and electrical equipment must be 
elevated above the BFE. Electrical supply via a service mast mounted on a freestanding 
concrete pylon was effective in preventing damage to buildings when overhead service 
dropped during the hurricane. Finally, there is typically a lack of sufficient attention to the 
design of seismic resistance of mechanical and electrical equipment.
Building Performance Assessment: Hurricane Georges In Puerto Rico 9-1 
Section 9 RECOMMENDATIONS 
9 Recommendations 
The recommendations of this report are intended to assist the Government of Puerto 
Rico in shaping its post-Hurricane Georges construction strategy and assist designers, 
contractors, and building owners in the construction of hazard-resistant buildings. These 
recommendations are based solely on the BPAT.s observations, an evaluation of relevant 
codes and regulations, and meetings with the Government of Puerto Rico. The 
recommendations apply primarily to the building code used in Puerto Rico at the time 
Hurricane Georges occurred and the newly adopted 1997 UBC. They also apply specifically 
to residential buildings, specific nonresidential buildings observed during the course of the 
investigation, and mid- and high-rise building envelopes. 
9.1 General Recommendations 
A disaster in a community offers an opportunity to reflect on the things that are 
important in our lives. Out of this reflection, a community can decide to take a stand against 
future natural disasters and promote sustainable development and disaster-resistant 
communities by committing to rebuild their homes, schools, businesses, and infrastructure 
consistent with effective mitigation techniques and approaches. 
As the people of Puerto Rico rebuild their lives, homes, and businesses there are a 
number of ways they can avoid the effects of future natural hazards. Some of these 
opportunities include: 
n Buildings designed to the new building regulations that provide greater 
protection against hurricanes and earthquakes. 
n New buildings permitted, built, and inspected to meet the new building 
regulations. 
n An upgraded electric power system so that power is quickly restored and critical 
services such as water and sewage treatment can continue to be provided. 
n A retrofit of existing buildings so their envelopes are not breached during a 
hurricane and do not collapse in an earthquake. 
n Special building precautions in areas with known hazards (such as floods, 
landslides, and tsunamis) or avoiding these areas altogether. 
More specific recommendations are included in the following subsections. Mitigating 
future losses, however, will not be accomplished by simply reading this report; mitigation is 
achieved when a community actively seeks and applies methods and approaches that will 
lessen the degree of damage sustained from natural hazards. Figure 9-1 illustrates a full range 
of successes and failures observed in a single community after Hurricane Georges.
9-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
RECOMMENDATIONS Section 9 
FIGURE 9-1 This photograph illustrates successes and failures in residential buildings observed after 
Hurricane Georges. A residential concrete building with no structural damage is seen in the center of 
the picture. At top right is a wood-frame building that is completely destroyed around a center room 
that was constructed of masonry. Other buildings in the photograph have damage that ranges from 
the total loss of the wood-frame building to the success of the concrete building. 
9.2 Training and Continuing Education 
The success and failure of buildings observed during Hurricane Georges offers important 
learning opportunities for Puerto Rico. Of greatest importance is the assurance that all buildings 
are permitted and appropriately designed, inspected, and constructed. The Government of 
Puerto Rico has adopted as emergency regulation the 1997 UBC, which more completely 
addresses the natural hazard risks of Puerto Rico than Planning Regulation 7. Adopting the 1997 
UBC is a significant change for government officials, design professionals, and contractors 
involved in the building industry and requires a significant training effort for these groups. 
9.2.1 Government of Puerto Rico Personnel 
To facilitate training of government personnel, ARPE completed a peer review by an 
independent third party, ICBO, the authors of the UBC. This peer review identified existing 
training courses and materials currently available that meet, or can be altered to meet, the 
immediate training needed by ARPE to implement the 1997 UBC. Training includes train-thetrainer 
courses so that ARPE can develop its own internal training resources. 
9.2.2 Design Professionals and Building Contractors 
The Government of Puerto Rico should continue to support positive mitigation education 
efforts undertaken by the Puerto Rico Civil Defense, Colegio de Ingenerios y Agrimensores,
Building Performance Assessment: Hurricane Georges In Puerto Rico 9-3 
Section 9 RECOMMENDATIONS 
Colegio de Arquitectos, and the University of Puerto Rico College of Engineering in Mayagüez. The 
recently published Huracanes en Puerto Rico: Guía de Mitigación de Daños provides useful 
information for design professionals and local homebuilders. This document should be reviewed 
and updated to ensure that it is compliant with the new building code and regulations. It should 
be reissued so that all parties involved in the building industry, from the design professional to the 
homeowner, will have accurate and useful information to mitigate against natural hazards. 
Programs such as the conferences sponsored by the Colegio de Ingenieros y Agrimensores on 
building envelope protection systems should be continued. New programs educating design 
professionals and builders should be developed to share state-of-the-art mitigation techniques 
that are being used throughout the United States for all natural hazard events (flood, wind, 
and seismic). 
ARPE, the Colegio de Ingenieros y Agrimensores, the Colegio de Arquitectos, FEMA, and ICBO 
are working together to develop a training schedule for the sections of the 1997 UBC that address 
natural hazards. 
9.3 Codes and Regulations 
Important improvements and revisions to the building code and planning regulations of 
Puerto Rico have taken place since Hurricane Georges. However, additional mitigation should still 
be implemented to improve the built environment. 
9.3.1 Planning Regulation 7 
ARPE and the Government of Puerto Rico have had numerous meetings with FEMA to discuss 
the preliminary findings of the BPAT and to identify ways to improve the building regulations and 
the enforcement of these regulations. As part of these efforts, the Government of Puerto Rico has 
adopted the 1997 UBC with local amendments as emergency regulation. In addition, Puerto Rico 
is also proceeding with legislation that will remove the exceptions that allowed some buildings to 
be built without a permit. 
ARPE anticipates that this new Certification and Building Board of Puerto Rico, under 
proposed legislation, will be in place by March 1999. One of the Board.s responsibilities will to be 
to consider and adopt updated building regulations, including the formal adoption of the 1997 
UBC, with amendments, as the new building code for Puerto Rico. 
Furthermore, the BPAT agrees with the Government of Puerto Rico.s decision to adopt the 
1997 UBC as an interim step toward adopting the International Building Code (IBC) when it 
becomes available. The following local amendments are also recommended for consideration to 
ensure that the 1997 UBC fully addresses factors affecting the built environment in Puerto Rico: 
1. In Chapter 15, Roofing: Require uplift testing, including prescriptive criteria for 
corrugated metal roofing, prohibit aggregate surfaced roofs (unless they are 
double surfaced or the parapet is of a minimum height), and provide prescriptive 
criteria for metal edge flashings/copings. Tile roofs should be prohibited because 
of the large volume of windborne debris they can create. If this is not acceptable, 
add provisions from the SBC, plus prescriptive criteria. 
2. Appendix Chapter 34, Repairs after a natural disaster: This should be looked at 
to determine if Puerto Rico wishes to expand this to address nonstructural 
envelope damage that frequently occurs following hurricanes.
9-4 Building Performance Assessment: Hurricane Georges In Puerto Rico 
RECOMMENDATIONS Section 9 
3. Adopt the Uniform Code for the Abatement of Dangerous Structures. 
4. Appendix Chapter 15, Reroofing: Normal re-roofing during the life of a building 
offers attractive opportunities for hazard mitigation of hurricanes. This appendix 
chapter should be adopted. 
5. Chapter 23, Wood: Require preservative treatment or naturally decay-resistant 
wood be used for termite resistance. 
6. Chapter 24, Glass: Require wind-resistance testing per ASTM E 1233. Add 
provisions related to missile impact resistance (use load criteria from Southern 
Building Code Congress International (SBCCI) STD 12 and test per 
ASTM E 1886)..1 
9.3.2 Floodplain Management Provisions of Planning Regulation 13 
ARPE and the Puerto Rico Planning Board should use information gathered by the CAV in May 
1998 and from the damage of Hurricane Georges to continue to educate homeowners on the risks 
involved in building in floodprone areas. A renewed effort in enforcement of Planning Regulation 
13, specifically in the permitting process and during the rebuilding process, may result in a 
significant reduction in property loss from future flood events. 
Procedures should also be in place to address situations when homeowners enclose ground 
level areas of buildings that were once properly elevated and flood resistant but are now noncompliant. 
In addition, a renewed effort is necessary for enforcement of Planning Regulation 13. 
Specific improvements should be made in the permitting and inspection processes during nondisaster 
times, but this is also especially important during the post-hurricane rebuilding process. 
During rebuilding efforts homeowners understandably rush to repair the damage to their houses, 
but their repairs often are not in compliance with the NFIP and Planning Regulation 13. Proper 
new construction, retrofitting of existing structures, and rebuilding of damaged buildings will 
result in significant reduction in property loss and human suffering from future flood events. 
Approximately 434,000 people live in identified floodplains in Puerto Rico. But there are 
approximately only 41,000 flood insurance policies currently in force, covering about 135,000 
individuals2. Hurricane Georges has provided Puerto Rico with an important opportunity to 
increase public awareness of flood risks. Purchasing flood insurance is one of the simplest actions 
communities and businesses can take to mitigate flood risk. It should be noted, however, that 
despite previous flood events, few of the eligible individuals in Puerto Rico have taken advantage 
of the NFIP group policies that were purchased following previous Presidentially-declared 
disasters under the Individual and Family Grant Program. FEMA and the Government of Puerto 
Rico must explain more effectively the benefits afforded by current flood insurance group policies 
in affected communities. 
1 A new ASTM missile load standard is nearing completion. When it becomes available it is recommended in lieu 
of STD 12. 
2 According to the 1990 census, average people per home and average people per family are as follows: 
3.31 people per home and 3.69 people per family. Source: Census Office of the Planning Board.
Building Performance Assessment: Hurricane Georges In Puerto Rico 9-5 
Section 9 RECOMMENDATIONS 
9.3.3 Evaluation, Submittals, and Product Approval 
A number of the BPAT.s recommendations relate to building construction but they are more 
appropriately addressed outside the building code. The BPAT recommends that the planning 
board evaluate the merit of the following recommendations: 
1. Issue a guideline for determining wind loads related to loads on rooftop heating, 
ventilation, and air conditioning (HVAC) equipment (guidance for this is not 
provided in ASCE 7-95). 
2. Consider product approval/submittals for components and cladding. Exterior 
Insulated Finishing Systems should require testing per ASTM E 1233 and 
perhaps include prescriptive criteria. 
3. Corrosion protection for clips, fasteners, metal panels, and flashing within 
3,000 feet of salt water could be addressed through product approval. It 
could also be addressed through an amendment to the building code. 
9.4 Essential Facilities 
Puerto Rico.s essential facilities should be evaluated for their vulnerability to natural 
hazard events. These facilities are critical to government response following a natural hazard 
event. The BPAT recommends that these buildings be evaluated under the provisions of the 
new building code in an effort to minimize the possibility of these facilities experiencing 
failures and loss of services during natural hazard events. Structures observed to perform at 
an unacceptable level should be retrofitted to improve building performance. This study 
should not be limited to such facilities as fire stations, police stations, and emergency 
operations centers, but should also include hospitals, emergency shelters (short- and longterm), 
and all buildings classified as essential facilities in ASCE 7-95. 
9.5 Residential Buildings 
The BPAT recommends the Government of Puerto Rico address vulnerabilities in 
residential construction through final adoption of the building code, as well as aggressive 
enforcement of these new regulations, to greatly improve the disaster resistance of 
residential buildings. Specifically, the design and construction of wood-frame buildings must 
be updated to greatly reduce the widespread damage that occurred to these structures 
during Hurricane Georges. Proper construction techniques and materials incorporated into 
the construction of these wood-frame buildings will greatly reduce their vulnerability to 
damage during natural hazard events. Construction of concrete and masonry structures 
should be regulated and inspected to ensure that they meet the new building code 
requirements, especially those regarding structural seismic issues. Finally, siting of residential 
buildings out of floodprone areas or requiring proper elevation through permitting 
enforcement will help to prevent damage and loss of property due to flooding. 
9.6 Structural and Architectural Performance 
The new building code will provide the building community with the tools to guide, evaluate, 
and regulate the construction and improvements of buildings in Puerto Rico. Based on the BPAT.s 
recommendations, the Government of Puerto Rico has adopted through emergency regulation a 
number of changes to the building codes and regulations that will improve the disaster resistance 
of both structural and architectural building systems. Puerto Rico must continue its proactive 
approach to updating such codes and regulations to minimize the damage that may occur during
9-6 Building Performance Assessment: Hurricane Georges In Puerto Rico 
RECOMMENDATIONS Section 9 
future flood, wind, or seismic events. Failure to update and improve the building environment, 
and the regulations that govern it, may result in repetitive damage and cost to Puerto Rico that 
otherwise could have been prevented. 
Model building codes often quantify loads that act on structures based on the recurrence 
interval of a particular natural hazard event: flood, wind, or earthquake. For natural hazard 
events, design flood conditions are based upon 100-year recurrence interval events. Design wind 
events are based on 50- or 100-year recurrence interval events. Design seismic events are based 
typically on 50-, 200-, or 500-year recurrence interval events. Although recurrence intervals are a 
useful concept to define natural hazards, they are frequently misapplied to explain risk. Table 9-1 
shows the risk (the probability of experiencing different events during specified yearly periods) 
and compares it to recurrence intervals. This, or similar tables, can be used by building owners to 
identify acceptable risks. Once the owner has determined an acceptable risk, the designer can 
choose the appropriate recurrence interval to use in design based on the life of the building. 
Based on an acceptable risk to the owner, the designer may choose a design event that is less 
frequent than required by the building code. For example, if the owner is building a 30-year 
building and wants a less than 6% chance of it failing in a hurricane, the designer would design 
for a 500-year recurrent interval. 
This table can also be used to broadly identify risk during a period of time. For example, 
during the next 20 years, there is a 45% chance that there will be an event with a recurrence 
interval of equal to or greater than a 50-year event. Puerto Rico has a 45% chance of seeing a 
hurricane as severe or more severe than Hurricane Georges in the next 30 years. 
9.7 Electric Power Distribution 
The BPAT recommends that the Government of Puerto Rico perform a study on the electrical 
power distribution system. The present system was improved after hurricanes in the 1990.s 
severely damaged the system. However, considerable damage was noted throughout the entire 
system after Hurricane Georges, indicating that improvements can still be made to reduce the 
system.s vulnerability to natural hazard events. 
TABLE 9-1 The probability of experiencing different events during specified yearly 
periods. 
Frequency/Recurrence Interval (Year Event) 
Life of Building or 
Length of Period (Years)
Building Performance Assessment: Hurricane Georges In Puerto Rico 
10References 
American Society of Civil Engineers, 1995. ASCE 7-95, Minimum Design Loads for 
Buildings and Other Structures. Washington, DC. 
Colegio de Ingenieros y Agrimensores de Puerto Rico, Defensa Civil Estatal de 
Puerto Rico, and Federal Emergency Management Agency, 1996. Huracanes en 
Puerto Rico: Guía de Mitigación de Daños. 
Earth Scientific Consultants. Analysis of the Tsunami Potential of Northwestern 
Puerto Rico. 
Federal Emergency Management Agency, 1998. Project Impact: Building a Disaster- 
Resistant Community. FEMA website. 
Hurricane Research Center, 1998. Preliminary Report. Key Biscayne, FL. 
National Oceanic and Atmospheric Administration, 1998. Georges Pummels 
Caribbean, Florida Keys and U.S. Gulf Coast. NOAA website. 
National Oceanic and Atmospheric Administration, 1998. The Saffir-Simpson 
Hurricane Scale. NOAA website. 
National Weather Service, 1998. Preliminary Post Hurricane Report. Hurricane 
Research Division. Miami, FL. NWS website. 
National Weather Service, 1998. Preliminary Report. San Juan, Puerto Rico. 
National Weather Service, San Juan, Puerto Rico, 1998. Tropical Storms and 
Hurricanes of Puerto Rico and the Virgin Islands. NWFSO website. 
New York Times, 1998. .Costs for Storm Relief Set a Red Cross Record.. October 18, 
1998. New York, NY. 
Southern Regional Climate Center, 1998. Hurricane Georges Storm Information. 
Baton Rouge, LA. SRCC website. 
United States Army Corp of Engineers, 1998. Hurricane Georges. Mobile District 
September 1998. Mobile, AL. U.S. Army Corp of Engineers website. 
University of Texas, 1998. The Perry-Castañeda Library Map Collection. Austin, TX. 
The University of Texas at Austin website. 
To order FEMA publications, call 800/480-2520 or write FEMA Distributional Facility, PO Box 
2012, Jessup, MD 20794-2012. 
Section 10 REFERENCES 
10-1
Building Performance Assessment: Hurricane Georges In Puerto Rico 
Members of the Building Performance Assessment 
Team for Hurricane Georges 
FEMA BPAT Members: 
JHUN DE LA CRUZ 
Insurance Underwriter Specialist 
Federal Insurance Administration 
Washington, DC 
BRET GATES 
Floodplain Management Specialist 
Mitigation Directorate, Headquarters 
Washington, DC 
KAREN HELBRECHT 
Hazard Mitigation Planner 
Mitigation Directorate, Headquarters 
Washington, DC 
CLIFFORD OLIVER, CEM 
Project Officer 
Mitigation Directorate, Headquarters 
Washington, DC 
PAUL TERTELL, P.E. 
Team Leader, Civil Engineer 
Mitigation Directorate, Headquarters 
Washington, DC 
BPAT Team Members: 
SUSAN COOKE ANASTASI 
Technical Editor 
URS Greiner Woodward Clyde Federal Services 
Gaithersburg, MD 
CARLOS COMPAÑY 
Wind Engineer 
Texas Tech University 
Lubbock, TX 
Appendix A 
A-1 
Appendix A MEMBERS OF THE BUILDING PERFORMANCE ASSESSMENT TEAM FOR HURRICANE GEORGES
A-2 Building Performance Assessment: Hurricane Georges In Puerto Rico 
DANIEL DEEGAN 
Civil Engineer 
URS Greiner Woodward Clyde Federal Services 
Atlanta, GA 
FRANK DOMINGUEZ, A.I.A. 
Architect 
McCullough-Dominguez 
San Juan, PR 
WILLIAM KERR 
Technical Writer 
Greenhorne & O.Mara, Inc. 
Greenbelt, MD 
MARK McCULLOUGH, A.I.A. 
Architect 
McCullough-Dominguez 
San Juan, PR 
THOMAS L. SMITH, A.I.A. 
Architect 
TLSmith Consulting, Inc. 
Rockton, IL 
E. SCOTT TEZAK, P.E. 
Structural Engineer 
Greenhorne & O.Mara, Inc. 
Greenbelt, MD
Building Performance Assessment: Hurricane Georges In Puerto Rico 
Presidential Disaster Declarations In 
Puerto Rico 
Appendix B 
B1 
Appendix B PRESIDENTIAL DISASTER DECLARATIONS IN PUERTO RICO 
Declaration Cause Declaration Emergency 
Date Number Number 
8/1/56 Hurricane 62 
5/26/64 Extreme Drought Conditions 170 
10/12/70 Heavy Rains and Flooding 296 
8/29/74 Extreme Drought Conditions 3002 
11/30/74 Flooding 455 
9/19/75 Tropical Storm Eloise 483 
9/2/79 Hurricane David 597 
5/31/85 Storms, Mud/land slides, Flooding 736 
10/10/85 Severe storms, Mudslides, Flooding 746 
7/10/86 Heavy Rains, Flooding, Mudslides 768 
12/17/87 Severe Storms, Flooding 805 
9/21/89 Hurricane Hugo 842 
1/22/92 Severe Storms, Flooding 931 
9/16/95 Hurricane Marilyn 1068 
9/11/96 Hurricane Hortense 1136 
11/21/96 Gas Leak Explosion 3124 
9/21/98 Hurricane Georges 1247 3130
Building Performance Assessment: Hurricane Georges In Puerto Rico 
Acknowledgments 
The BPAT would like to thank the following people for their assistance and/or review of the 
BPAT report: 
William Coulbourne, P.E., Greenhorne & O.Mara, Inc. 
Ismael Pagán Trinidad, University of Puerto Rico Mayagüez Campus 
Dr. Raul Zapata, University of Puerto Rico Mayagüez Campus 
Dr. Ricardo Lopez, University of Puerto Rico Mayagüez Campus 
Philip Line, American Forest and Paper Association 
Richard Okawa, P.E., V.P., International Conference of Building Officials 
Eng. Jorge Garcia Faneytth, ARPE 
Eng. Carlos O. Gonzalez, ARPE 
Eng. Rafael Morales, Government of Puerto Rico Planning Board 
Tom Kane, FEMA, Deputy Federal Coordinator - Mitigation for Puerto Rico 
Harold Spedding, FEMA - Puerto Rico 
Terrence A. Leppellere, P.E., V.P., Building Officials & Code Administration 
International 
José R. Caballero-Mercado, President, Government of Puerto Rico Planning Board 
Rafael Mojica, National Weather Service, San Juan, Puerto Rico 
Jianming Yin, Ph.D., Applied Insurance Research, Inc. 
ACKNOWLEDGMENTS