The questions about how long the various products last does not have a numerical answer.
The answer is much more narrative and dependent on a huge number of variables. To be succinct, I believe PVC lasts longer for two reasons:
- With PVC, the seams are welded and literally permanent as opposed to glued together. By welding a seam with either hot air or chemicals, the material is bonded to itself on the molecular level just like when the material was first made. The bond is permanent and is stronger than the surrounding material. By gluing a seam, we depend on the sticking power of a second material. These materials are highly engineered and last a good long time but are not permanent. Being exposed to water greatly shortens the life of the seam.
- With PVC, the penetration flashings are most often made from the same material as the rest of the roof. With EPDM, a much more pliable and weaker material is used. EPDM systems most often begin to fail at this critical place.
One of the caveats to all of this is that the longevity or relative quality of a roof is mostly dependent on the contractor installing it. With the exact same product, either PVC or EPDM, a roof can last 5 years or it can last 35. The most powerful determining factor is how well the contractor manages and accounts for the huge number of variables mentioned earlier. With that being said, I believe that PVC systems offer fewer variables so would last longer with the larger number of different contractors.
PVC roofing has been on the market for over 40 years and has been well studied and tested. Early failures of the material were largely due to some manufacturers not getting the plasticizer right, or for allowing contractors to install the material in direct contact with incompatible materials. Both of those deficiencies were corrected over 30 years ago and the product has performed very well since then.
A well engineered and installed PVC Roof, where the flashing materials are the same reinforced material as the rest of the roof, can last in excess of 25 years.
If you have any questions about the lifespan of your roof or how to make it last longer, contact us today!