EPDM Roofing Pros & Cons
EPDM is particularly well suited for classic flat or “low-sloped” roofs common in commercial construction. One of the biggest reasons EPDM has become popular is the average cost to install and maintain. Compared to other roofing options, EPDM generally will run about 10% less than the standard TPO install. Compared to mod-bit (modified bitumen) it is much safter to install while being cleaner looking.
What is an EPDM roof?
EPDM stands for Ethylene Propylene Diene Monomer - in layman's terms a rubber roof. Specifically it is a synthetic rubber and the two primary ingredients of EPDM (ethylene and propylene) are manufactured using a combination of oil and natural gas and while black is the most common color for EPDM installs, white is also commonly available.
It is both flexible and extremely durable and because it is installed in sheets, often does not have any seams, meaning less lifetime leaks. On top of all of that, because the material is a synthetic rubber, it is almost impossible to burn and has even been known to actually slow or even stop a building fire’s progress.
That often means a lower installation cost, lower insurance premium and longer lifetime value than the most common type of roof it replaces (tar and pitch roofs).
TPO Roofing, known as an energy star rated eco-friendly flat roofing option.
Modified Bitumen is the classic standard in flat roofing, but has recently fallen in popularity.
PVC Roofing is popular for being heat reflective, lightweight, & eco-friendly
See an overview of our commercial roofing service options and comparisons.
Extend the life of your roof at a fraction of the cost of a full flat roof replacement.
See an overview of our industrial roofing service options and comparisons.
How do you apply EPDM Roofing?
EPDM is widely known for an easy installation, which leads to less labor cost for you, the customer, plus better guaranteed coverage of warranties.
The first steps are cleaning off of the existing roof and the laying of a minimum of one half inch insulation cover sheets (polyisocyanurate boards). These boards are fastened across the entire deck of the roof. These cover sheets are usually rated in what’s called an “R” value.
After all of the insulation cover sheets are laid in place, the next step is to roll out the EPDM roofing material or “rubber membrane.” Membranes are rolled out uniformly, then folded back over themselves so that a bonding adhesive can be applied to keep the membrane securely in place.
The application of the adhesive is critical: it must be worked on slowly and spread evenly to guarantee a good seal. Normally this is where you might see a roofing contractor using a push broom over the top of the EPDM rubber as they’re smoothing out the sealing glue and eliminating small imperfections like wrinkles.
This process is repeated until the roof is complete! No blow-torching or disruptions to normal business operations necessary.
How long do rubber membranes last? How long should an EPDM roof last?
Properly installed EPDM roofs last between 22 and 35 years before minor repair work is needed, and usually last for up to 40, even 50 years. It is widely known as the “forever roof” of the flat roofing world.
Important to know that EPDM manufacturer warranties will cover both labor and material costs, however, every job must be inspected by the manufacturer and the work done by a certified installer AND installed to spec.
This roof inspection does add an additional cost, but also gives a full guarantee and full warranty on all aspects of the new rubber roof. Additionally, for warranties to be valid they have to use 100% the same manufacturers products - no mixing and matching allowed.
Plus, the manufacturing process of EPDM uses very little energy and the material itself is 100% recyclable. So not only does the roof last forever, but the material can be easily reused, making this roof material a favorite among homes and businesses looking to go green.
What are some of the cons of EPDM versus other types of flat roof materials?
For property managers, rubber roofing is not a do-it-yourself kind of project, and even for many roofing professionals the process is not easy to master. While the overall installation has less steps and less risk than other types of roofing, like modified bitumen, the devil is in the details.
An inexperienced roofing installer will easily miss problem areas like around vents pipes and other roof features that require fitting. These areas, where you cannot cleanly and evenly lay down a sheet of membrane, is the most often cited problem area for minor leaks and cause for not passing the manufacturer's warranty inspections. Therefore, it’s critical to get a reliable professional roofing company to install the EPDM roofing system correctly the first time.
Another commonly cited problem with EPDM comes down to aesthetics: especially among homeowners, some do not like the colors (since it’s primarily manufactured only in black and white). However, there are acrylic coatings are designed specifically to be used with EPDM and are flexible to match to any color you’d like.
What are my options for putting on a new EPDM roof?
The precise work needed is going to vary on what kind of roof you currently have over your building. For example, petroleum products generally eat away at the rubber membranes over time, so you have a couple options
1.) Remove the old roof
This option is most common with old tar and pitch roofs, which also usually are going to require an asbestos tested and remediated given the age and date when this style of roofing was typically installed.
While costlier, this will generally be the most efficient long-term solution for you and your building’s infrastructure integrity.
2.) Roll over modified bitumen
If you have a modified bitumen roof, EPDM can be rolled over mod bit installs, but they will require a special patching cement that does not use any tar.
EPDM vs. Modified Bitumen
Modified Bitumen (mod bit), which has been a staple in the roofing world since the 60’s and the replacement of old BUR (built up roofs) has a few advantages: more than any other roofing material, it can take a lot of abuse (good for high foot traffic areas). However, because a blow torch has to be used to mold the material into place, the degree of installation error is much higher. More installation errors mean more seams (more leak possibilities) and an uglier looking roof.
Ironically, while mod bit can stand up better to more foot traffic and is itself more durable than EPDM, it’s very rarely perfectly installed, even by seasoned professionals, which leads to a shorter life expectancy (more seams) and more repair work needed. Plus the actual application of mod bit is messy, smells bad and is difficult to find the source of leaks down the road.
With mod bit there’s always the possibility of burning down the building, leading to a higher insurance cost and it does not stand up to ponding water very well. No roof is perfectly level and ponding water is when water “sits” in one spot on the roof without properly draining off the side. Left alone, ponding water often causes significant damage to flat roofs.
EPDM on the other hand is easier to install, is very reliable and stands up to ponding water exceptionally well. Side-by-side the only weak point in EPDM vs. Mod Bit is that EPDM is less durable against high foot traffic. However, this can be solved by installing a ballast system with walking pads.
With EPDM, even if roof seams and flashings at vulnerable points fail, they can be easily repaired or replaced to extend the lifetime of the roof even further.