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Historic Preservation - Technical Procedures

Spectitle:

Installing Lead Stone Flashing To Protect Masonry Joints

Procedure code:

0765601R

Source:

Fed Bldg/Uspo/Spokane, Wa - Gsa/Pbs

Division:

Thermal And Moisture Protection

Section:

Lead Flashing

Last Modified:

02/24/2012

Details:

Installing Lead Stone Flashing To Protect Masonry Joints



INSTALLING LEAD STONE FLASHING TO PROTECT MASONRY JOINTS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on weatherproofing
         vulnerable masonry joints by embedding a soft lead strip
         into a caulking compound/sealant filled joint.

    B.   This type of work is often necessary when unknown
         building movement causes the failure of existing joint
         caulk/sealant in locations such as a masonry/stone
         parapet, coping, balustrade, railing, cornice, belt
         course ledges, or any other exterior masonry/stone
         features where the top surface is exposed.  This also
         includes corner and fillet joints where a horizontal
         surface joins to a vertical surface; with horizontal
         protection to extend down over front and back edges 2" or
         to an appropriate stopping point to protect the exposed
         corner.

    C.   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).

1.02 SYSTEM DESCRIPTION

    A.   Stone flashing is a weatherproofing product, manufactured
         from lead, which is designed to be used with a building
         sealant for the weatherproofing and protection of masonry
         joints.  It consists of a molded cap or fillet surface
         with a splined tang for anchoring in the sealant filled
         mortar joint; manufactured in a selection of sizes, and
         in continuous strips for field cutting and fitting.

1.03 SUBMITTALS

    A.   Manufacturers' information, shop drawings (manufacturer's
         standard detail sheets), materials lists and certificates
         for the products proposed for use.

    B.   Samples:  12" long pieces of each type of stone flashing
         proposed for use.

1.04 QUALITY ASSURANCE

    A.   Restoration Specialist:  Work must be performed by a firm
         having not less than 5 years successful experience in
         comparable masonry restoration projects and employing
         personnel skilled in the restoration processes and
         operations indicated.

1.05 WARRANTY

    A.   Provide copies of all manufacturer's guarantees of
         materials and installation, duly signed and dated.

    B.   Include all warranty inspections by a manufacturer's
         representative necessary to effect the guarantee of
         material performance and its installation.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Weathercap, Inc.
         P.O. Box 1776
         Slidell, LA  70459-1776
         504/649-4000

2.02 MATERIALS

    A.   Tee Caps:  Lead Stone Flashing strips (Weathercap, Inc.),
         or approved equal.

         1.   Use size of strips as recommended by sealant
              manufacturer and compatible with style and
              configuration of existing.

         2.   Strips should be of sufficient size to cover the
              joint width, plus a percentage allowance for
              anticipated joint movement, plus 1/4".

    B.   Sealant:  As recommended by Tee Cap manufacturer.  See
         also 07900-01-S for guidance.  Test to make sure sealant
         does not stain masonry.

2.03 EQUIPMENT

    A.   1" masking tape

    B.   Putty knife

    C.   Heavy gloves


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Determine the extremes of joint movement using a scribe
         kit (available from sealant manufacturer); measurement of
         anticipated and known joint movement is necessary in
         determining the appropriate size of tee cap to use.

3.02 PREPARATION

    A.   Verify that joints to have stone flashing strips are
         raked or cut out to the correct depth and clean.

3.03 ERECTION, INSTALLATION, APPLICATION

    NOTE:  WEAR GLOVES WHEN WORKING WITH LEAD PRODUCTS AND WASH
    HANDS THOROUGHLY WHEN FINISHED WITH WORK.

    A.   Fitting Tee Cap:

         1.   Mark off width of selected tee cap on the
              masonry/stone surface and apply 1"  masking tape
              lateral to marks.

         2.   Pre-fit or shape and cut tee cap strips to closely
              conform to the profile of the stone substrate as
              required before setting.

         3.   Select width to overlap joint edges not less than
              1/8".

         4.   Cut strips to lay in a single full length of each
              joint wherever possible with an end turn-down over
              front and back faces of ledges and copings a
              minimum of 1" or to drop edge.

         5.   Make all joints in tee cap neatly mitered, coped,
              or butted to produce close fitting, weather
              resisting joint protection; notch strips as
              recommended by manufacturer.

         6.   Apply metal primer to tee cap if required.

    B.   Sealing and Installing Tee Cap:  Install sealants in
         accordance with manufacturer's recommendations.

         1.   If required, install backer rod to a depth of 1/4"
              below tip of anchor shaft when tee cap is set in
              place.

         2.   Prime stone, if required.

         3.   Fill joint with sealant to a height of
              approximately 1/8" above the adjacent masonry
              surface.  Follow manufacturer's instructions.

         4.   Set preformed tee cap strip into the sealant bed,
              pressed down firmly to the stone surface so bonding
              grooves are solidly filled and no voids exist
              between tee cap and masonry.

         5.   Clean off excess sealant compound using a putty
              knife and leave adjacent masonry clean.

         6.   Carefully remove masking tape from adjacent
              surfaces.

                        END OF SECTION