WATERPROOFING MASONRY JOINTS USING MOLTEN LEAD, LEAD WOOL OR A
PROPRIETARY LEAD CAP SYSTEM


THIS PROCEDURE USES LEAD, A HIGHLY TOXIC SUBSTANCE.  THE WORKPLACE
MUST BE ADEQUATELY PROTECTED TO PREVENT INGESTION OF LEAD BY
WORKERS, OR THE SPREAD OF LEAD BEYOND THE WORK SITE.  ALL
ENVIRONMENTAL LAWS MUST BE FOLLOWED CONCERNING CLEAN-UP AND
DISPOSAL OF WASTE MATERIALS.


PART 1---GENERAL

1.01 SUMMARY

     A.   This procedure provides guidance on waterproofing masonry
          joints using molten lead, lead wool (similar to steel
          wool), or a proprietary lead capping system which uses
          appropriate caulks or sealants.  

          1.   Leading joints is a traditional technique of
               filling joints to obtain the maximum possible
               waterproofing.

          2.   Molten lead and lead wool are often called lead
               caulk.

     B.   Leading, in one of these three forms, is most commonly
          found, and appropriately used for:

          1.   Joints between stone units in the same plane, i.e.
               coping joints and balustrades; cross joints on
               cornices and belt courses; top joints on window and
               door lintels, entrance porticos, brackets,
               pilasters, watertables and any other piece of
               masonry which projects beyond the face of the
               building.

          2.   Joints between stone units set approximately at
               right angles to each other, i.e. at parapet or side
               walls, or at stair risers and treads.

          3.   Expansion and control joints.

          4.   Anchor holes, i.e. iron fence members into masonry
               or concrete.

          5.   Reglets - horizontal reglets generally filled with
               molten lead, vertical generally with lead wool. 
               (Molten lead should NOT used where lead wedges are
               also used to help secure flashing into reglet.)

     C.   Safety Precautions:  Provide protective clothing to
          workers to protect them from extremely high temperatures
          of molten lead.

     D.   See 01100-07-S for general project guidelines to be
          reviewed along with this procedure.  These guidelines
          cover the following sections:

          1.   Safety Precautions

          2.   Historic Structures Precautions

          3.   Submittals

          4.   Quality Assurance

          5.   Delivery, Storage and Handling

          6.   Project/Site Conditions

          7.   Sequencing and Scheduling

          8.   General Protection (Surface and Surrounding)

          These guidelines should be reviewed prior to performing
          this procedure and should be followed, when applicable,
          along with recommendations from the Regional Historic
          Preservation Officer (RHPO).


PART 2---PRODUCTS

2.01 MANUFACTURERS

     A.   Weathercap, Inc.
          P.O. Box 1776
          Slidell, LA  70459-1776
          501/649-4000

          -or-

          1925 Juan Tabo N.E.
          B-252
          Albuquerque, NM  87112
          601/255-2058

     B.   Dow Corning Corporation
          P.O. Box 994
          Midland, MI  48686-0994
          517/496-4000

     C.   GE Silicones
          260 Hudson River Road
          Waterford, NY  12188
          800/255-8886

     D.   H.B. Fuller Automotive Technical Systems
          P.O. Box 14556, Northridge Station
          Dayton, OH  45413-0056
          800/543-7570, or 513/890-3150

2.02 MATERIALS

     A.   Pure Lead:  Available in 5-lb. bars at plumbing supply
          centers (NOT hardware superstores).

     B.   Lead Wool:  Available at plumbing supply centers.

     C.   "Weathercap Type A (Flat) or Type B (90o Cove) Cap" as
          required by joint being sealed, or approved equal.

     D.   Exterior grade caulk as appropriate for type of joint
          being sealed (for use with Weathercap), such as "Corning
          790" or "Corning 791" (Dow Corning), "Ultraglaze 400" or
          ""Silpruf 2000" (GE Silicones), "PTI 738", "PTI 707" or
          "PTI 7130" (H.B. Fuller Automotive Technical Systems), or
          approved equal.

2.03 EQUIPMENT

     A.   Heat-proof crucible and source of heat to bring solid
          lead to melting point of 621o F (320o C).

     B.   Ladle to pour molten lead into joint.

     C.   Hammer and chisels (variety of sizes) for packing lead
          wool into joints.

     D.   Hack saw (18T x 12-in. blade), pliers and clippers to
          cut, notch and bend lead cap as required by installation.


PART 3---EXECUTION

3.01 PREPARATION

     A.   Protection:

          1.   Work must be done on a warm day, while the masonry
               itself is warm, so that extreme high temperature of
               molten lead does not cause masonry to crack.

          2.   Make sure masonry is completely dry.

          3.   If using proprietary capping system, measure width
               of joint to determine width of cap required.  Width
               required equals measurement of joint opening, plus
               the maximum percentage of joint movement
               experienced per scribe test, plus 1/4-inch.

3.02 ERECTION, INSTALLATION, APPLICATION

     A.   Waterproofing with Molten Lead (horizontal joints only)
          and Lead Wool:

          1.   Rake and clean joints of all loose mortar and
               debris.

          2.   For long joints or reglets into which molten lead
               is to be poured, temporarily plug ends with heat
               resistant material.

          3.   Pour molten lead, or pack lead wool tightly, into
               joint to seal.  If molten lead is being used to
               waterproof the joint between a stone base and an
               iron picket or newel, make sure bottom of hole has
               lead in it before setting iron piece.

     B.   Waterproofing Using a Proprietary Lead Capping System:

          1.   Rake and clean joint(s).

          2.   Mark off width of cap onto masonry.

          3.   Apply 1-inch wide masking tape along marks.

          4.   Using a clean, dry cap piece, cut, notch and/or
               miter sections of cap as required to fit joint.

               a.   Outside angles:  notch anchor shaft of cap
                    piece a full 90o and bend to fit angle of
                    masonry being sealed.

               b.   Inside angle:  make single cut in anchor shaft
                    and bend to fit angle of masonry being sealed.

               c.   Outside curves:  notch anchor shaft at
                    intervals to allow cap to fit curve.

               d.   Inside curves:  make straight cuts in anchor
                    shaft at intervals to allow cap to fit curve.

          5.   Pre-fit and contour cap after cutting or notching
               anchor shaft to fit joint.  Lift cap out of joint
               and apply metal primer to cap, if required by
               sealant manufacturer.  Allow to dry until tacky.

          6.   Seat foam backer rod into masonry joint to proper
               compressed depth.

          7.   Prime masonry if required by sealant manufacturer. 
               Allow to dry until tacky.

          8.   Apply small bead of sealant/caulk to tacky metal
               surface to prevent air entrapment when seated in
               place.

          9.   Fill masonry joint to approximately 1/8-inch above
               face of stone with sealant/caulking compound.

          10.  Set cap in place, pressing firmly into sealant/
               caulking compound for seating and shaping.  Turn
               down at all angles and edges.

          11.  Remove excess sealant/caulking compound with a
               putty knife, being careful not to get excess on
               masonry and leaving finished joint neat and clean.

          12.  Remove masking tape.

                          END OF SECTION