Seaming Membrane Panels with Seam Tape

After adhering the membrane sheets so that the width of the seam is the width of the seam tape used, remove excess chalk from a chalk line. You can do this by snapping the line into the air and then chalk a line 13mm from the leading seam edge.


Fold the top sheet back to expose the seam area. (Hint: A small piece of seam tape that is tacky on both sides is useful to tack the membrane back.)

If the EPDM membrane is contaminated with dirt, dust or debris, clean the seam area with Membrane Cleaner on a cotton cloth before applying the Seam Tape Primer Plus. Using the Scrub Pad, apply the Seam Tape Primer to the area with back and forth strokes. Use moderate pressure until the seam surface attains a smooth black appearance. Apply the Seam Tape Primer past the seam edge to the chalk line. Allow the primer to dry.

If Solvent Based Bonding Adhesive is in the area to be seamed, apply duct tape to the adhesive-covered membrane area and roll with a hand roller. Peel off duct tape. If the adhesive remains, repeat the process. If is in area to be seamed, remove with damp cloth.

Seam Tape comes in rolls of 7.62cm x  7.62mtrs and 7.62cms x 30.48mtrs.

Unroll the Seam Tape along the length of the seam, tape side down, aligning the Seam Tape paper with the chalk line. Using moderate pressure, draw the Scrub Pad or roller along the Seam Tape release paper. This will set the Seam Tape into place and keep air from being trapped under the tape. Fold the top membrane onto the Seam Tape release paper.


Reaching under the top ply of membrane, pull the release paper away from the Seam Tape at a 45° angle to the seam. While removing the paper, draw your hand across the seam, from the back to the leading edge. This will prevent wrinkles and fish mouths from forming in the seam. After the paper is removed, roll the entire length of the seam with a steel hand roller, first, across the seam, and then the length of the seam.

IMPORTANT! If the Seam Tape does not visibly extend beyond the leading seam edge, the edge (figure 14d) should be cleaned with Membrane Cleaner and caulked with Lap Caulk.

Note: When splicing Seam Tape, overlap each piece a minimum of 25mm and firmly roll with a steel hand roller.