In this guide, we'll discuss...
- Materials and Coatings
- Membrane Thickness
- Advantages and Disadvantages
- Finding a Qualified Contractor
Ethylene propylene diene terpolymer, or EPDM, is a type of single-ply rubber roofing material that has been around since the 1960s; and it continues to be a popular choice in commercial and residential flat roof applications today.
EPDM is composed primarily of ethylene and propylene, which are derived from natural gas and oil.
EPDM materials come manufactured in various thicknesses, available as non-reinforced or reinforced sheets, and vulcanized or non-vulcanized membranes. Each has different physical properties and applications fitted for specific commercial environments.
With more than one billion square feet of EPDM membrane installed worldwide, it’s one of the most widely-used roofing materials on the planet, particularly in the commercial roofing sector. White EPDM roofing membrane is becoming increasingly popular due to its UV reflecting and heat-reducing properties.
Many top-level manufacturers sell EPDM coatings. Each offers premium protection and durability, but they often require an experienced commercial contractor for proper installation.
Some of the top choices for EPDM on the market include:
- GAF Top Coat
- Firestone AcryliTop
Your commercial contractor should provide information about their coating of choice. It’s always a good idea to contact at least three contractors to get the best idea of what’s appropriate for your business.
EPDM roofing membrane is a flexible rubber material available in 45 mil, 60 mil, and 90 mil thicknesses.
These membranes are available as non-reinforced or reinforced sheets. Reinforced membranes have an internal fabric totally encapsulated within the sheet and available in its own thicknesses. On occasion, a fleece layer may be added to the underside of the membrane that acts as a built-in underlayment.
With its superior flexibility and extreme durability, EPDM membranes can contour to unusual roof shapes.
One of the primary advantages of EPDM roofs is how easy it is to install. EPDM is installed in large sheets, making it far less intensive than other flat roofing systems.
1. Clean the roof
Start by ensuring the surface of the roof is free of all dirt, debris, and moisture, and that all the roof’s decking is securely fastened.
2. Lay out the membrane
Next, lay the EPDM membrane into position and allow 3” of material to hang over the roof’s edge. Allow the membrane to sit for a full 30 minutes to remove wrinkles. Then, fold the membrane back over itself and prepare the bonding adhesive.
3. Apply the adhesive
Make sure the membrane is in position and all the wrinkles are out. Then, evenly apply the adhesive to the exposed roof and the back of the membrane. Make sure to avoid applying adhesive to membrane areas that will be seamed. Let the adhesive dry, checking with a finger if necessary.
4. Secure the membrane
Next, roll the membrane onto the roof where the adhesive has been applied. Go slowly and evenly to reduce the chance of wrinkles. Going over the membrane with a push broom will ensure a proper adhesion.
- Resists extreme temperatures and holds up well to standing water
- Available in white – reflects up to 80% of UV rays and saves on AC cooling costs in the summer (black EPDM is paintable using water-based acrylic paint)
- Durable – life expectancy of up to 50 years when installed/maintained correctly (warranties typically do not exceed 20 years)
- Easy to install
- Lightweight (with the exception of ballasted EPDM roofing)
- Class A fire resistance
- Easy to repair
- A poorly installed EPDM roof can spring leaks along the seams quite easily
- Oils, solvents, grease, and other contaminants can degrade the membrane
- Cannot be applied over or in contact with creosote, coal tar pitch, or Pentra-based materials
- 1 - 2% shrinkage is common over time, particularly on ballasted installations. This isn’t an issue for smaller roofs, but large commercial roofs may suffer from this problem.
According to ASTM standards, EPDM roofing membrane can withstand temperatures as low as -49 degrees F before the membrane begins to become brittle and is lab-tested to withstand temperatures up to 240 degrees F during a 4-week testing period.
Additionally, field testing in hot and humid parts of the country, like Southern Florida, have shown positive results.
Today’s EPDM roofing materials can withstand the shock of bitter-cold temperatures and remain flexible and strong in extremely hot environments. It also performs well in areas of the country where both extremes are experienced, such as desert environments.
LEARN MORE: The Complete Commercial Roofing Guide
EPDM is an affordable roofing option, making it one of the top choices when it comes to flat roofing.
As a general reference, EPDM pricing ranges between $4 and $6 per square foot.
However, there are several factors that come into play when it comes to cost, including:
- the quality and thickness of the membrane used
- removal costs — roof insulation layers, existing roofing material, etc.
- your geographic location
- the size and complexity of your roof
Manufacturer defects are rare with EPDM roofing. According to the American Society of Home Inspectors, about 95% of all EPDM roof repairs are caused by installation errors. This is why it’s extremely important to choose a qualified EPDM roofing contractor to install or repair your roof.
If your EPDM roof is in need of serious repair, it’s always a good idea to hire a professional contractor. However, small holes can be repaired by the property owner using a patch.
How to Perform a Patch Repair:
1. Clean the Surface
Clean the roof surface thoroughly to allow the patch to adhere directly to the membrane. Start by clearing off dirt, debris, and carbon black residue from the area you wish to patch.
2. Measure the Patch
When cutting the patch material, allow it to extend past the area where the repair is necessary. Leave 2” in all directions from the leading edge of the damaged area.
3. Prime the Roof
Apply a thin coat of primer to the membrane surface using a medium nap roller. Make sure the primer extends past all the edges where the patch is to be applied. This allows the patch to properly adhere to the membrane.
4. Apply the Patch
Then, press the patch firmly into place using a steel roller, as it applies even pressure and removes trapped air from the patch. To finish, apply lap sealant around the leading edge to protect against moisture from getting under the new patch.
It’s relatively easy to repair EPDM roofing material, although you should never use asphalt-based products for repairs, as this can degrade the quality and integrity of the membrane. Approved sealants and EPDM repair patches generally take well and will extend the life of the roof.
Poor maintenance and general weathering/old age are the causes of most EPDM roof damage. Rubber roofs are nearly maintenance-free. Clear the rooftop of leaves, tree limbs, standing water and other debris at least once per year to maximize the performance and lifespan of the roof.
LEARN MORE: Commercial Roof Repair 101
It’s not difficult to find an experienced and qualified EPDM roofing contractor since it’s such a popular choice for commercial and flat-roofing applications.
Hometown makes it easy for customers to compare roofing contractors. You’ll have access to a variety of options and receive quotes for your project.