How to Repair a Rubber EPDM Roof

Patching Sections to Extend the Life of Your Roof

By
Christophor Jurin
Christophor Jurin
Christophor Jurin is the founder and CEO of Construct-Ed, an online construction training website. He also has worked in roofing for more than eight years.
Learn more about The Spruce's Editorial Process
Updated on 12/05/22
Reviewed by
Kelly Bacon
Kelly Bacon
Reviewed by Kelly Bacon
Kelly Bacon is a licensed general contractor with over 40 years of experience in construction, home building and remodeling, and commercial building. He is a member of The Spruce Home Improvement Review Board.
Learn more about The Spruce's Review Board
Roofing PVC membrane in rolls placed on the roof of a hall

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In This Article
Project Overview
  • Working Time: 1 hr
  • Total Time: 2 hrs
  • Skill Level: Intermediate
  • Estimated Cost: $20 to $300

Long-lasting repairs to 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 incompatible with asphalt-based products. Never use any roof cement flashing and asphalt-based roof coating, including aluminum roof coating. These materials will contaminate the EPDM rubber membrane, leading to a more extensive repair.

Have your roof cleaned and inspected periodically to evaluate the roof coating. If you need to reseal a rubber roof, it might need a special fabric applied, a base coat, and an elastomeric coating as a topcoat sealant. Or you might be able to use a peel-and-stick roofing patch made of EPDM material. If you need an adhesive, use a specially formulated product called "an EDPM rubber roofing adhesive." EPDM roofs can be repaired or patched if the original roof material is in good shape and the seams are holding.

What is an EPDM Rubber Roof?

EPDM stands for ethylene propylene diene terpolymer, an extremely durable synthetic rubber roofing membrane commonly used for roofing low-slope buildings. The main ingredients are derived from oil and natural gas.

Patching EPDM Roofs

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 bonding the patch. These kits can be expensive, but they may consist of enough material to make several repairs.

Other coatings like liquid rubber, liquid butyl, and rubber sealants can also waterproof and patch spots that have leaks.

How to Repair a Rubber EPDM Roof

What You'll Need

Equipment / Tools

  • Tape measure
  • Shears or utility knife
  • Paintbrush or paint roller with medium-nap cover
  • Roller

Materials

  • All-purpose household cleaner
  • Rags
  • EPDM patch material
  • EPDM roof primer
  • Lap sealant
  • Old credit card

Instructions

  1. Prepare the Roof Surface

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

    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 where the patch will be applied. Use cloth rags to remove the oxidation from the surface of the EPDM and all traces of moisture.

  2. Cut the Patch to Size

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

  3. 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 edges of where the patch will go.

  4. Install the Repair Patch

    Methods for installing the patch vary depending on what type of repair kit you have:

    Using a pressure-sensitive patch: Remove the paper or film backing from the patch, apply the patch to the roof membrane, and press it down firmly. Roll the patch in multiple directions with a 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 the roof surface in the patch area, following the manufacturer's instructions. 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.

    Note: The adhesive must be designed for sealing EPDM to EPDM. Do not use yellow glue designed for sealing EPDM to substrates or insulation boards.

    Tip

    It may be helpful to lay the patch over the damaged area and trace around it with a marker pen. Spread the roof EPDM adhesive up to the lines left by the trace. This will keep a much cleaner-looking patch. Be careful and accurate when placing the patch, as the cement sticks on contact and can't be adjusted.

  5. Seal the Patch Edges

    Apply a heavy bead of EPDM lap sealant around the patch's perimeter, sealing all 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.

FAQ
  • What are common problems with EDPM roofs?

    Common problems with EDPM roofs include punctures or membrane damage, shrinkage, failing seams, and incorrect installation.

  • When should I replace my EDPM roof?

    EPDM roofs last about 20 to 25 years, depending on whether you regularly inspect and maintain the roof.

  • How do I find a leak in my EDPM roof?

    You will need to go to your roof and inspect the spot where you think the leak is occurring. Search for a hole, tear, damaged flashing, missing caulking, or a busted seam.

  • Can you walk on an EDPM roof?

    You can walk on an EDPM roof. It's fine for light foot traffic.