Welcome to the default, or old school, material for flat roof installations. It’s technical name: Ethylene Propylene Diene Monomer is a mouthful. While it is simply a rubber material, we’ll go with EPDM since everyone else does. This product competes directly with TPO and PVC as membrane type roofing material. This one though tends to only be used on flat roofs.
Some might be wondering why not just use the more traditional roofing materials like asphalt shingles. Well, traditional roofing materials normally come in a shingle or tile form designed for sloped water-shedding roofs, not waterproof ones.
If you were to use roofing shingles on a low-slope or flat roof, then any accumulated pooling water would rise underneath the asphalt shingles and seep through inside the house (similar to what happens with ice dams on asphalt shingle roofs), leading to severe issues like mold, rot, and damage to the roof deck and interior of the house.
Thus, a waterproofing membrane approach has been in place for nearly a half century to provide an impenetrable waterproof barrier that can reliably protect the structure with a low-sloped roof.
EPDM Pricing and Value
EPDM is the least expensive of the three primary membrane types, but it isn’t cheap. The material is very durable.
Since the early 1960s, EPDM has been the material of choice in canals and other irrigation systems prior to becoming a successful material for waterproofing roofs.
It’s estimated to have 1 billion square feet of EPDM rubber membranes installed throughout the world’s roofs. This is partially due to its relative durability, ease of installation and its competitive pricing.
Average Cost Per Sq. Ft. Installed
On the low end, you can plan to spend around $4.50 to $6.50 per sq. ft. for the installation of an EPDM rubber membrane on a flat roof. — The low-end pricing, although not very common, would be on par with asphalt shingles pricing, which tells you how affordable it can be. $6.50 to $10.50 per sq. ft. installed would be the high-end pricing and would likely be for a thicker or solar-reflective rubber membrane, with the job done by experienced flat roof specialists.
What about DIY for EPDM?
The DIY approach is viable, because installation is not complicated. With TPO and PVC roofs, you need special skills and tools like hot air welders (whether hand-held or robots) for proper installation.
With EPDM, you need the sheets, which are sold in as large as 50 feet wide by 200-foot-long pieces, some glue and preferably some experience in achieving a successful installation.
Home Depot and Lowe’s sell rolls of 10 x 25 feet for around $170 and $225, respectively. Add another $80 for the glue, or bonding adhesive (sold in 3-gallon containers) and $25 for long armed roller and you’re set to go.
When it comes to value or return on investment, that’s another matter. Our Advantages and Disadvantages section below help identify the balance of lasting value vs. known issues.
The reality is EPDM roofs last 7 to 15 years on average before requiring a replacement (less likely) or resealing (more likely). With EPDM liquid roof coatings, repairs and resealing can extend the lifespan of the rubber membrane roof and re-institute the waterproof barrier properties from the original installation.
A Further Look At EPDM
The fundamental characteristics of EPDM membrane are it is black and rubber. It is understood to be very flexible. Though that is with regards to the vulcanized (cured) form of the material. It’s rarely referenced as such because it’s the typical form.
Non-vulcanized (uncured) is less flexible and is referenced as the form of the material used for flashing or sealing seams between roof and penetrations from extruding pipes or other such roofing features.
While black is easily the most common color, EPDM does sell with a white surface, or laminated top. This is done to compete with the TPO and PVC options and to achieve the CoolRoof ratings and/or energy-efficiency performance effects. Yet, those other materials are vastly superior in reflecting UV rays, whereas EPDM either is not as efficient, or it’s a matter of an ongoing debate.
Note that EPDM liquid roof coatings are a different product from EPDM rubber membranes.
Being black though has its benefits, and is said to block UV rays, or absorb heat, which in colder climates is desired. If for any reason, black doesn’t appeal to you, using an acrylic paint on the surface does allow you to have unlimited color options.
EPDM is known to require ongoing maintenance with the seams due to how its seams hold up or dry out and become compromised over time. Resealing and re-coating are the most viable options and really do extend the life of the roof.
Where EPDM has disadvantage is how well it holds up to heat, as it can break apart. In cool weather, the opposite is true, or it is strongly believed that EPDM holds up better in extreme cold than say TPO.
If the material isn’t breaking apart, but the glued seams are needing repair, then resealing them or re-coating the entire roof will sustain the life of the roof, and the EPDM material.
EPDM membrane is produced in a range of thicknesses, from 45 to 95 millimeters. Additionally, it is available as a non-reinforced or reinforced sheet, which depends on the application.
Maintenance is simple cleaning, and we do mean simple. Clearing debris with water washing only. The caveat with EPDM is that liquid solvent cleaners, especially citric based ones, can damage the material.
Advantages of an EPDM Roof
- holds up to hail, heavy rain, wind, and extreme cold better than other membrane materials
- ease of installation
- less expensive than PVC and TPO roofs
- re-coating with liquid EPDM can extend the life of the roof
- proper installation by quality experts will deliver warranties as long as 30 years
Disadvantages of an EPDM Roof
- maintenance issues if not properly installed, re-coating or resealing sometime after 7 years is likely
- not as energy efficient as TPO and PVC
- color options are greatly limited, though the material can be painted
- doesn’t handle well in higher temperature climates
- typical cleaning materials will seriously damage the product, likely voiding warranties