How to Coat a Rubber Membrane Roof

Over time the rubber membrane on a roof deteriorates, causing leaks that need repair.

Liquid rubber coats a rubber roof membrane on flat and low sloping roofs.Liquid rubber coats a rubber roof membrane on flat and low sloping roofs.
Extreme weather conditions can tear rubber. The resultant patch repairs can look unsightly. Apply a coating over the rubber membrane to create a uniform look that mitigates the aesthetics and elongates the life span of the roof membrane. Liquid rubber coatings are Ethylene Propylene Diene Monomer or EPDM rubber solutions that cover a rubber roof membrane in a seamless application that is suitable for the do-it-yourself market. A liquid rubber coating is easy to apply if you follow the correct surface preparation techniques.

Sweep the rubber roof with a push broom to clear all loose debris from the surface. Use a scrubbing brush and a solution of water mixed with detergent to clean the rubber membrane of dirt and grease or oil stains.

Kill penetrating mildew and mold from the rubber membrane with a solution of one part bleach to three parts water. Pour the solution over the fungal growth. Allow the solution to evaporate naturally. Remove silicone-based sealant from any part of the membrane that you want to coat. Silicone prevents adhesion of the rubber coating.

Cover tears and exposed edges in the rubber membrane with lengths of butyl tape. Use a seam roller over the surface to firmly adhere the tape. Reglue any loose rubber to the roof deck with roofing tar. Allow it to dry before applying a rubber coating.

Mark an 80 square foot section of roof using a measuring tape and a chalk line. Pour 2 gallons of liquid rubber coating into a 4-gallon container. Position the mixing shaft attachment onto the electric drill. Place the shaft into the center of the container. Switch on the electric drill. Pour in the rubber activator. Continue to mix for 15 minutes.

Pour the rubber coating over the marked area in a zigzag motion to apply an even quantity across the surface. Use a rubber squeegee to spread the liquid over the rubber membrane. Roll a paint roller over the surface in long strokes to flatten the rubber coating out evenly and remove any air from the solution.

Use a paintbrush to apply the rubber coating to areas too small to use the squeegee. Mark out additional roof sections on the rubber membrane with a chalk line so that you use 1 gallon of rubber coating per 40 square feet. Continue to mix quantities of rubber coating. Apply it in the same way as before until the rubber roof membrane is completely covered.

Allow the rubber coating to dry for 20 hours in a minimum 70-degree Fahrenheit ambient temperature before walking on the roof. Allow the coating to fully cure for at least a week in the same temperature, and for longer in lower temperatures.

Things You Will Need

  • Push broom
  • Scrubbing brush
  • Detergent
  • Bleach
  • Butyl tape
  • Seam roller
  • Roofing tar
  • Measuring tape
  • Chalk line
  • Liquid rubber
  • 4-gallon container
  • Mixing shaft attachment
  • Electric drill
  • Rubber activator
  • Rubber squeegee
  • Paint roller
  • Paintbrush
  • Safety glasses
  • Rubber gloves

Tip

  • Don't worry if the rubber membrane expands during the coating application and drying time. The membrane shrinks back into position over a few weeks.

Warning

  • Wear safety glasses and rubber gloves to protect yourself from chemical splashes.

About the Author

Residing in the coastal county of Devon, England, Jane Humphries has been writing since 2004. Writing for "British Mensa" nationally and regionally, Humphries has also held key roles within the High IQ Society. She received a Bachelor of Science, honors, in psychology with combined studies covering biology, statistics, economics, politics and sociology.