Thermoset membranes are “rubber like”. All materials within this product class possess the quality of recovery. When stretched, they will elongate, but will return to their original shape when released. This ability to stretch is reduced if the membrane is reinforced. This section contains general repair procedures for thermoset membranes.

Typical Thermoset Membrane Repair Procedure (Adhesive)

• Prepare the surface by removing debris, contaminants and ballast from the surface of the membrane or flashing to be repaired. Any field applied coating must be removed prior to repairing the membrane. The area to be prepared should extend at least 150 mm (6 in) beyond where the perimeter of the patch will lap onto the existing membrane.
• Wash the area with a solution of mild soap and water. Scrub with a stiff bristle brush. Dirt must be removed from the area to be patched. Ensure that the cleaned area extends a minimum of 300 mm (12 in) beyond the defect.
• Rinse thoroughly with clean water and allow the membrane to dry.
• Apply weathered membrane cleaner to the existing membrane surfaces in the repair area as recommended by the membrane manufacturer and allow to dry.
• Cut a piece of like membrane large enough to extend 150 mm (6 in) beyond any part of the defect. Round corners of the patch to prevent peeling of square corners.
• Thoroughly clean the surface of the membrane to be repaired and backside of the patch material with a clean, absorbent, lint-free cloth  and cleaner recommended by the original membrane manufacturer or the repair membrane supplier. Turn the cloth frequently and replace when dirty to prevent dirt and contaminants from being scrubbed into the membrane. Allow the solvent-wash to thoroughly flash-off  and  dry. The colour of the cleaned membrane should be solid, without streaks. Apply the manufacturer recommended primer to both surfaces to be mated and allow to dry.
• Apply the proper adhesive to the membrane and the patch in accordance with the instructions provided with the adhesive. Allow time for the adhesive to dry so that it will not stick or string to the touch of a clean, dry finger. Apply pressure to the adhesive film by hand to determine if it has dried throughout its thickness.
• When adhesive is ready, mate the two surfaces and smooth out with pressure from a gloved hand. Do not stretch or wrinkle the patch. Roll the patch with a roller to ensure solid contact of the two adhesive films.
• Apply lap sealant. For additional security, the patch can be stripped in with 150 mm (6 in) wide flashing material.
• If ballast has been removed, redistribute the ballast over the exposed area after the lap sealant has skinned over.

Typical Thermoset Membrane Repair Procedure (Tape)

• Prepare the surface by removing debris, contaminants and ballast from the surface of the membrane or flashing to be repaired. Any field applied coating must be removed prior to performing repairs to the membrane. The area to be prepared should extend at least 150 mm (6 in) beyond the perimeter of the patch.
• Wash the area with a solution of mild soap and water. Scrub with a stiff bristle brush. All dirt must be removed from the area to be patched. Ensure that the cleaned area extends a minimum of 150 mm (6 in) beyond the defect. Rinse thoroughly with clean water and allow the membrane to dry.
• Apply weathered membrane cleaner to the existing membrane surfaces in the repair area as recommended by the membrane manufacturer and allow to dry.
• After the membrane has dried, stir tape primer thoroughly and apply the primer to the membrane with a brush, scrubbing pad, or lint-free rag. Prime an area the actual length and width of the repair piece. While the primer is drying, cut a piece of pre-taped coverstrip (or flashing) the right size, allowing at least a 75 mm (3 in) overlap of the area to be repaired.
• Round the corners of the patch with scissors to prevent peeling of square corners. Peel back the release paper on the back of the pre-taped coverstrip and install the coverstrip centered over the area to be repaired with the adhesive side turned toward the primed surface. Smooth this patch into place as it is applied, taking care to avoid wrinkles. Roll the patch in all directions with a rubber roller to ensure proper adhesion.
• Apply lap sealant.
• If ballast has been removed, re-distribute the ballast over the exposed area after the lap sealant has skinned over.

Laps and Splices

Open laps or splices should be pulled back to a sound part of the seam or splice and any debris removed.

• If water leakage has occurred, cut open the membrane and inspect the insulation, vapour retarder and/or roof deck for damage. Remove and replace wet or damaged insulation, vapour retarder and/or roof deck as required. Properly attach new, dry insulation with the thickness of the existing insulation and compatible with the other roof components.
• After cleaning the open lap area, the existing open lap or splice should be glued together with seam adhesive prior to the installation of a patch.
• Complete the repair as described in the Typical Thermoset Membrane Repair Procedure (Adhesive or Tape) above.

Fasteners

• Loose fasteners should be removed and replaced with new fasteners and plates in an adjacent location. Do not install the same size fastener into an existing hole. If the hole is stripped and the fastener cannot be repositioned, install an oversized fastener.
• For each new fastener, provide a patch that extends 75 mm (3 in) beyond the hole created and fastener/plate installed.
• Complete the repair as described in the Typical Thermoset Membrane Repair Procedure (Adhesive or Tape) above.

Ballast Scour

If ballast scour is discovered, inspect the membrane for damage and repair if necessary.

Re-distribute the ballast being careful not to damage the membrane.

Pitch Pockets

If the filler material has cracked, pulled away from the side(s) of the pocket, or is below the level of the top of the pan, remove the loose or damaged sealant material.

• Wire brush and clean the object extending through the pan and the existing metal pan.
• Thoroughly mix and pour in the new two component sealant.
• Crown the sealer above the top of the penetration pocket to provide drainage away from the penetration.