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? Well, those usually come in tile form, and between each tile poses a chance for water to seep in, or pool up, which will lead to rot on the roofing deck. Thus, the membrane approach has been in place for nearly a half century to provide a waterproof barrier.
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 $3.00 to $4.00 per sq. ft. for the installation of EPDM rubber 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. $5.50 to $7.50 per sq. ft. would be the high end, and would likely be a thicker material, or reflective of having the job done by quality flat roof professionals.
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 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 $205 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 needing replacement (less likely) or resealing (more likely). With EPDM liquid roof coating, repairs and resealing can extend the life of the roof and re-institute the waterproof barrier from 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 achieve the cool roof effect. Yet, those other materials are vastly superior in reflecting UV rays, where as EPDM either is not, or it’s a matter of ongoing debate.
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 due to how its seams hold up 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