A T-Joint is formed when two sheets of cured EPDM form a seam that travels under, or over, a third ply. The center of the "T" is where the middle sheet ends and the top sheet bridges over the middle sheet. This T-Joint can provide opportunity for water to seep under the membrane. To avoid problems at this area, a T-Joint patch should be installed as follows:
1. Clean the membrane with Membrane Cleaner.
2. Prime area at least four inches (4") in all directions from the T-Joint.
3. Cut a piece of Uncured Flashing with Tape 3" larger than the T-Joint(s) and round corners. A single T-Joint patch can be made large enough to accommodate more than one T-Joint, as shown in Figure 24 b.
4. Remove backing, place over T-Joint and roll with hand roller.
Figure 24 — AREAS WHERE T-JOINT PATCHES ARE REQUIRED:
Figure 24 a
WHERE A FIELD SEAM TRAVELS UNDER A WALL FLASHING.
Figure 24 b
WHERE A COVER STRIP TRAVELS UNDER A PIPE BOOT OR OTHER FLASHING.
Figure 24 c
WHERE A HORIZONTAL SEAM WILL LAP OVER, OR TRAVERSE A VERTICAL SEAM.
IMPORTANT: ONLY UNCURED FLASHING WITH TAPE, CUT TO SIZE, IS USED FOR T-JOINT PATCH. ALL T-JOINT PATCHES SHOULD BE THOROUGHLY ROLLED WITH A STEEL HAND ROLLER.