T-Joints

A T-Joint is formed when two sheets of cured EPDM form a seam that travels under, or over, a third ply. The centre of the “T” is where the middle sheet ends and the top sheet bridges over the middle sheet. This T-Joint can provide an opportunity for water to seep under the membrane. To avoid this problem a T-Joint patch should be installed as follows:

  1. Clean the membrane with Membrane Cleaner.
  2. Prime the area at least 10.16cms in all directions from the T-Joint.
  3. Cut a piece of Uncured Flashing with Tape 7.62cms 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 (see Figure 24 b).
  4. Remove backing, place over T-Joint and roll with hand roller.

IMPORTANT: Only Uncured Flashing with Tape, cut to size, should be used for T-Joint patch. All T-Joint patches should be thoroughly rolled with a steel hand roller.