Repairing a Rubber EPDM Roof

  • 01 of 05

    Introduction

    black rubber roof
    EPDM roofing systems are a common choice for low sloped roofing installations for residential applications. Photo © Jurin Roofing Services www.jurinroofing.com

    EPDM roofing systems, sometimes referred to as rubber roofs, are a very common choice for low sloped roofing installations for residential applications. They have an extended service life with a life expectancy of 15 to 20 years for most designs and applications. They are safer to install when compared to modified roof systems that require the use of an open flame torch or hot asphalt and are easier to maintain and repair should leaks or damage ever occur.

    Making good, long-lasting repairs to an...MORE EPDM system depends on selecting the right repair materials and on correct preparation of the repair area. Using improper materials or methods to repair and maintain your EPDM roof system can lead to damages to the roof membrane, as well as a reduced life expectancy and premature failure of the roof system.

    What Products Can’t Be Used On My Rubber Roof?

    EPDM roofing membrane is a synthetic rubber membrane. EPDM, or rubber, is not compatible with asphalt-based products. This includes any type of roof cement flashing, as well as any type of asphalt-based roof coating containing aluminum roof coating. These types of products should not be used to maintain or repair an EPDM roof membrane system.

    The dangers of using asphalt projects on an EPDM system are very real. The contaminated membrane will need to be cut out and replaced, and if the extent of the contamination is widespread, the entire roof system may need to be replaced. 

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  • 02 of 05

    Preparing the Roof Surface

    The next step in repairing your EPDM roof system is to properly prepare the roof surface to receive the patch. EPDM has carbon contained within the membrane, and as the membrane ages, the sheet begins to develop a carbon film that can be seen if you rub your hand across the sheet. If it is black EPDM, you will have carbon black on the surface of your hand. This carbon black film, as well as dirt and other oxidation, must be cleaned from the surface of the sheet to ensure that the patch will...MORE stick to the surface of the roof membrane.

    Clean the Roof Repair Area

    In order to clean the surface, use a cleaner that does not leave a residue on the membrane after the area dries. Many manufacturers recommend a cleaner such as Simple Green or Spic n’ 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, then wipe the surface of the area down 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 05

    Sizing and Cutting the Repair Patch

    Measure the roof repair patch before applying the primer. Lay the patch material over the area to be patched, and outline a patch that will extend at least 2" beyond the damaged area in all directions. Once you have laid out the patch, cut the roof repair material to fit. Clip or round the corners of the patch to avoid any sharp corners that can be caught and lifted by foot traffic on the roof surface.

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  • 04 of 05

    Priming the Repair Area

    Next, apply a thin coat of primer to the membrane surface where the patch is to be applied, using a paint roller with a medium-nap roller cover or paintbrush.  When applying the primer, ensure that it extends past all edges of where the patch is to be applied. This will ensure that all leading edges of the EPDM patch will adhere to the roof membrane.

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  • 05 of 05

    Installing the Repair Patch

    Repair materials 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.

    Pressure-Sensitive Roof Repair Patch

    If you are using a pressure-sensitive roof repair material, remove the paper or film backing from the patch and apply the patch firmly down to the surface of the roof system. It is best to use a steel roller to apply the patch to the surface of the roof because it...MORE will press any trapped air out from under the repair patch. Apply a bead of EPDM lap sealant around the leading edge of the patch to provide additional protection against water infiltration.

    Non-Pressure-Sensitive Roof Repair Patch

    If you are using a repair material that does not have a pressure-sensitive backing, use a single-ply EPDM adhesive to adhere the patch to the roof surface. The adhesive must be designed for sealing EPDM to EPDM--do not use yellow glue designed for sealing EPDM to substrates or insulation board.

    Apply the adhesive to the underside of the membrane patch and to the surface of the area to be patched. Allow the adhesive to flash off until it is no longer tacky to the touch. After the glue has flashed off,  carefully mate the patch material to the surface of the roof. Once applied, use the steel roller to roll the entire patch to make certain that it has properly mated to the existing EPDM roof membrane. Apply a bead of EPDM lap sealant around the leading edge of the patch to provide additional protection against water infiltration.