PRESERVATION TECH NOTES:  WINDOWS Number 3

EXTERIOR STORM WINDOWS:  CASEMENT DESIGN WOODEN STORM SASH

Wayne Trissler
National Trust for Historic Preservation

and

Charles E. Fisher
Preservation Assistance Division
National Park Service


This standard includes the bulk of information contained in the
original Preservation Tech Notes developed by the National Park
Service and the Center for Architectural Conservation at Georgia
Tech.  The Preservation Tech Notes are case studies of exemplary
projects designed to provide specific examples of sound
preservation techniques.  To obtain a complete copy of The Window
publications, including figures and illustrations, please contact: 

          Historic Preservation Education Foundation
          P.O. Box 77160
          Washington, DC  20013-7160

The Window Handbook, jointly prepared by the National Park Service,
Preservation Assistance Division and the Center for Architectural
Conservation at Georgia Tech, also contains all of the Tech Notes
on Windows and is available for purchase from the Historic
Preservation Education Foundation for $32.00.  The Window Workbook
is available for $49.00.  The two publications together can be
purchased for $72.00.


LYNDHURST GATEHOUSE
Tarrytown, New York

***INTRODUCTION***

The two-story stone gatehouse on the grounds of the Lyndhurst
Estate in Tarrytown, New York, is part of a National Historic
Landmark that was once the home of railroad magnate Jay Gould.  The
property is owned today by the National Trust for Historic
Preservation and is open to the public.  Built in 1864, the South
Gatehouse is used as a private residence for a caretaker.

The windows, with ashlar surrounds on the first floor and
decorative wood detailing on the second, are prominent features of
the building.  The original double-hung wooden windows, with tow-
over-two pane configuration, have survived in relatively good
condition.  The 13 windows in the gatehouse are of five different
sizes; all but one have an arched head in the upper sash and a
thick vertical muntin with a center bead.

The windows on this structure were fitted with custom-made exterior
storm windows that meet specified performance criteria and yet
minimize both damage and visual obstruction to the historic
windows.


***DESIGN PROBLEM***

In many buildings where the historic windows are significant and
will be preserved in the rehabilitation project, the installation
of storm windows for energy conservation can require innovative
features or some adaptation to standard window designs.  This may
be necessary in order to minimize damage to historic fabric and to
preserve the visual qualities of the historic windows.

Such an approach was taken in the rehabilitation of the South
Gatehouse windows at Lyndhurst.  As guidance, the following
criteria were established beforehand for designing the new storm
windows:

1.   The new design had to be sympathetic with the historic
     character of the building.

2.   The windows needed to remain operable to allow for ventilation
     and also for use as possible fire exits.

3.   Energy conservation objectives had to be met.

4.   Only minimal damage to the historic windows could occur in
     mounting the storm windows and inconspicuous hardware had to
     be used.

5.   Provisions had to be made for insect screens.


***DESIGN SOLUTION***

A storm window was subsequently developed that meets all of the
above requirements.  The storm window, in the style of a single
casement, was installed on the outside of each of the historic
windows and attached to the existing frame.  The arched-headed
wooden storm window with one-over-one glass panes matched the size
of the original double-hung sash.  Molding details similar to the
original were incorporated in the new storm sash.  Each of the two
panes in the storm sash was set in thin aluminum frames and secured
in the wood storm window with standard clips.  This installation
technique enables the storm panels to be easily removed by a person
on the inside of the house and replaced during the summer with
screens.

Mounting hardware consisted of pin-in-socket hinges which required
the drilling of only two holes in the existing frame.  The hinges
allow the window to open casement-style for egress and ventilation
purposes.


***MEASUREMENT AND FABRICATION***

Each of the window openings was measured and dimensional
irregularities identified.  The distance from the sill to the
bottom of the historic meeting rail was also measured so that a
corresponding muntin on the storm sash could be fabricated.

Depending on availability, one inch thick white pine and cypress
were selected.  Lumber was milled to proper dimensions in the shop
facilities on site.  The rails and stiles were cut to length with
allowances made for the curvature of the window arch.

In making arches for the five windows, a template of Masonite was
first made for each.  By fitting the template to the historic arch,
it was then possible to trace the top of each on a piece of 5«"
wide pine or cypress to make the top rails for each window.

Dowels were used to join the rails and stiles.  Two holes for 3/8"
by 2" dowels were drilled for each joint with the exception of the
top rail.  For the arch, only one hole per joint was made due to
the lack of space.

Before the windows were fitted together, the inner moldings on the
rails and stiles were cut on the shaper to match the 9/16" quarter
round molding on the historic sash.


***ASSEMBLY***

In fitting the windows together, the parts were glued at the joints
with resorcinol glue, dowels inserted, and the clamps attached
while the glue hardened overnight.  After the joinery was
completed, the tops of the stiles were cut to fit the curvature of
the arch.  For the first floor windows, a 5/8" by 9/16" rabbet was
cut along the outer edge to allow the window to fit over the
existing moldings on the historic window frame.

The windows were then fitted to each opening and bottoms planed to
a slight angle corresponding to the sill.  Two weep holes were cut
in the bottom to allow condensation to escape, and the windows were
permanently labeled as to their location in the building.

Custom-made stainless steel hinges of a pin-in-socket design were
attached to the left side, top and bottom of each window.  The
windows were then sanded, treated with a non-toxic preservative,
and primed with an oil-alkyd paint.


***INSERTS***

The two aluminum-frame storm inserts for each window were
constructed of molding cut on a mitre.  The top pane of glass was
cut to follow the arch of the top rail, and the units were then
assembled and labeled.  Screens were cut and assembled in a similar
manner.  The aluminum frames were roughened with sandpaper and
painted with two finish coats.  After the paint had thoroughly
dried, the storm inserts were installed with small aluminum hold-
downs on the inside of each window.


***FINAL INSTALLATION***

In hanging the windows, 3/4" holes were drilled in the sill and the
top of the historic window frame to accommodate the stainless steel
anchor.  The holes were thoroughly soaked with the same wood
preservative used on the sash, then filled with a polysulfide caulk
before the anchor was inserted.  After the windows were installed,
1 inch hook-eyes were attached to secure the windows shut while a
second hook-eye, 1 foot long, was installed on each window to hold
it in a fixed position when opened.


***PROJECT EVALUATION***

The storm window used on the gatehouse incorporates several
desirable design features.  It is a successful preservation
solution by maintaining the arched head of the windows;
proportioning the framing members along the basic lines of the
primary sash; matching the materials of the historic window and
avoiding damage to historic fabric.  The casement design does not
impede use of the windows for emergency egress, and the panel
inserts set on the inside of the storm frame provide for convenient
seasonal change from storm to screen units without relying on
obtrusive multiple-jamb tracks.  While the custom hardware is
perhaps a luxury feature, for economy purposes standard hardware
could have been substituted.  The storm windows, moreover, are
detailed so that almost any local mill could easily make them. 
This sensitive storm window design has widespread applicability to
many other historic buildings where owners are seeking to maintain
and upgrade the existing historic windows in an aesthetically
pleasing and practical manner.


***PROJECT DATA***

BUILDING:

-    South Gatehouse
     Lyndhurst Estate
     National Trust for Historic Preservation
     635 South Broadway
     Tarrytown, New York

PROJECT DATE:  January-March, 1980

PROJECT STAFF:

-    Wayne Trissler, Apprentice and Joseph Lewes, Master
     Restorationist
     National Trust Restoration Workshop
     635 South Broadway
     Tarrytown, New York

MATERIALS:

-    Stainless Steel Hardware - Wesco F.G. Corporation
     Bridge Street
     Box 3
     Irvington, New York

PROJECT COSTS:

-    The fabrication of the windows was undertaken by an apprentice
     at the National Trust Restoration Workshop at Lyndhurst.  No
     cost figures are available.

                              END OF SECTION