By Dymon Brady

If you are in the market for a flat roof membrane, you may have noticed the plethora of options, including some strange abbreviated names such as TPO, PVC and EPDM.  We have an article describing what a TPO membrane is, as well as PVC membrane and why we avoid installing PVC at Brady Roofing.  Now it is time to address a staple membrane in the flat roofing industry: EPDM.

EPDM stands for Ethylene Propylene Diene PolyMethylene.  But for the rest of this article, we will simply call it EPDM.  It is a synthetic rubber roofing membrane composed of natural gas and oil combined with diene to create a flexible membrane.  When formulated correctly, it can be extremely durable.  This flexible material is then dusted with talc, or a similar dusting agent, and cured to ensure it’s durability against sunlight, moisture, roof-top traffic and temperature extremes.

EPDM, by nature, is black.  Many manufacturers have created a white on black EPDM membrane to help this material become more energy efficient.  This is a viable option.  Just be aware that a white on black membrane is just that: a black membrane covered with a separate white material and then laminated together.  The white portion of the membrane tends to wear away, leaving the EPDM black again by the time the warranty period is up.

Are you trying to decide between installing TPO or EPDM on your roof?  We have created a quick infographic for you to help you compare the two products:

TPO EPDM Infographic

Read on for an in-depth comparison.

Price

TPO is actually more expensive upfront for the material than EPDM.  However, the installation process is less expensive because TPO can be welded with hot air, while EPDM is installed via adhesive.  Overall, TPO tends to be less expensive.

History

EPDM has an excellent track record.  In fact, it was introduced as a roofing product over 50 years ago.  When installed correctly, EPDM is known to be dependable and durable, especially outperforming other products in cold climates.  TPO is a relatively new product, and has been reformulated several times.  However, in the last 12 years it has shown indications of fulling lasting it’s warranty period.

Energy Efficiency

A roof’s energy efficiency has become more and more important to our environmentally conscious customers.  The truth is, how much money an “energy efficient” roof will save you is directly dependant on wheher your building has more ‘cooling days’ (days where you run the air conditioner) or ‘heating days’ (days where you run the heater.

Because EPDM is typically black, it will help to keep your building warmer in the winter, while raising cooling costs in the summer.  If you have more ‘heating days’ EPDM could be a great choice for you.  TPO is typically white, and so will lower cooling costs in the summer and probably raise them in the winter.

Installation Process

As mentioned earlier, TPO is easier and less expensive to install than EPDM.  However, either membrane can be effective if they are installed correctly.  EPDM is attached at the seams via an adhesive.  The installation process begins much as it does with TPO.  We roll out the material and then fasten the membrane to the roof.  Then the work begins on the seams.  These seams must be primed, taped, secured and brushed off with a broom before they can finally be rolled with a tool and combined together.  When installing TPO, we simply roll out the material, fasten the membrane, and then weld the seam.

It is worth mentioning that EPDM comes in much larger rolls than TPO, which means less seams.  Because the seams on a roof are the most vulnerable areas for leaks, it has been argued that EPDM may be less prone to leaks.  However, we believe that if the roof is installed correctly, this is less of a concern.  TPO roofs have 3-4 times stronger seams than EPDM because they are heat welded.

Maintenance

EPDM is known to be an excellent option for roofs that require a lot of traffic because of the nature of the material.  However, be aware that if an EPDM roof does happen to be punctured, it can be extremely difficult to locate the area of the leak.  Some punctures are near impossible to locate unless it is a warm day after it has just rained, allowing the water to move up through the punctured area.

A TPO roof may require walking pads to ensure that high traffic areas are not worn down or punctured.  If a puncture does occur, they are easily located and repaired.

In conclusion, EPDM is an excellent choice for cold climates or for roofs that require a lot of traffic on them. This material is durable and time tested.  If you are looking for long term security, EPDM may be the roof for you.  It is true that no matter what material you choose for your roof, the quality will depend on the level of expertise of the installers combined with the quality of material.  Contact Brady Roofing today for a fast, free estimate, and we can help meet your needs!

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