Installing Lead Stone Flashing To Protect Masonry Joints
- Procedure code:
- Fed Bldg/Uspo/Spokane, Wa - Gsa/Pbs
- Thermal and Moisture Protection
- Lead Flashing
- Last Modified:
INSTALLING LEAD STONE FLASHING TO PROTECT MASONRY JOINTS
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
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
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.
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
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.
A. Weathercap, Inc.
A. Tee Caps: Lead Stone Flashing strips (Weathercap, Inc., NucLead),
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.
A. 1" masking tape
B. Putty knife
C. Heavy gloves
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.
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
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
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
END OF SECTION