Repairing a Rubber EPDM Roof

  • 01 of 06

    Choosing the Right Patch Materials

    Black rubber roof
    Jurin Roofing Services

    Long-lasting repairs on an EPDM roofing system requires the right repair materials and careful prep of the repair area. EPDM roofing membrane is made with synthetic rubber and is not compatible with asphalt-based products. This includes any type of roof cement flashing as well as any asphalt-based roof coating, including aluminum roof coating. These materials will contaminate the EPDM rubber membrane, requiring replacement.

    Patching materials for EPDM roofing are sold as either standard membrane materials that require separate adhesive or as pressure-sensitive materials that have the adhesive pre-applied to the underside of the membrane. Patching materials also are sold in kits that include cleaner, primer, and roller for adhering the patch.

    Supplies Needed:

    • All-purpose household cleaner
    • Rags
    • Tape measure
    • Shears or utility knife
    • EPDM patch material 
    • EPDM roof primer
    • Paintbrush or paint roller with medium-nap cover
    • Steel roller
    • Lap sealant
    • Old credit card
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  • 02 of 06

    Prepare the Roof Surface

    The first step in repairing your EPDM roof is to prepare the roof surface to receive the patch. EPDM has carbon contained within the membrane, and as the membrane ages, the sheet develops a carbon film that can be seen if you rub your hand across the sheet. This carbon film, as well as dirt and other oxidation, must be cleaned from the surface of the sheet to ensure that the patch will stick to the roof membrane.

    To clean the roof surface, use a cleaner that does not leave a residue. Many manufacturers recommend an all-purpose household cleaner, such as Simple Green or Spic and Span. Wash the patch area, cleaning well beyond the area where the patch will be applied. Use cloth rags to remove the oxidation from the surface of the EPDM and to remove all traces of moisture from the patch area.

    It is important that all dirt, oxidation, and carbon black are removed to ensure that the new patch sticks to the roof surface and not the film. Cleaning the roof surface properly will allow the patch to adhere directly to the membrane, improving its long-term performance.

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  • 03 of 06

    Cut the Patch to Size

    Measure the patch area. If necessary, cut the patch material so it extends at least 2 inches beyond the damaged area in all directions, using heavy shears or a utility knife to cut the patch. Clip or round the corners of the patch to remove sharp corners that can be caught and lifted by foot traffic on the roof surface.

    Continue to 4 of 6 below.
  • 04 of 06

    Prime the Repair Area

    Apply a thin coat of EPDM roofing primer to the membrane surface where the patch is to be applied, using a paintbrush or a paint roller with a medium-nap roller cover. Make sure the primer extends beyond all of the edges of where the patch will go.

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  • 05 of 06

    Install the Repair Patch

    Using a pressure-sensitive patch: Remove the paper or film backing from the patch, apply the patch to the roof membrane, and press it firmly. Roll the patch in multiple directions with a steel roller to remove any air bubbles and fully bond the patch.

    Using a glue-down patch: Apply a single-ply EPDM adhesive to the back of the patch and to the roof surface in the patch area, following the manufacturer's instructions. Note: The adhesive must be designed for sealing EPDM to EPDM. Do not use yellow glue designed for sealing EPDM to substrates or insulation board. Allow the adhesive to flash off until it is no longer tacky to the touch. Press the patch onto the roof, then roll it with a steel roller, moving back and forth in multiple directions, to remove air bubbles and bond the patch.

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  • 06 of 06

    Seal the Patch Edges

    Apply a heavy bead of EPDM lap sealant around the perimeter of the patch, sealing all of the edges. Smooth and flatten the sealant with an old credit card or similar plastic tool so the edges are well sealed and the sealant feathers onto the surrounding surface.