Negatives of Acrylic Coatings on Flat Roofs

Acrylic roof coatings provide many benefits. They are cost-effective, highly durable, and easy to work with. But when it comes to restoring flat roof substrates with ponding water issues and poor drainage, an acrylic coating system can be quite problematic.

The Challenges of Acrylic Roof Coatings

Acrylic elastomeric roof coatings were originally designed in the 1970s for restoring sloped metal roofs. Over time, coating manufacturers and contractors realized that acrylics could be used effectively on other commercial roofing substrates, with one caveat: the roof must drain well.

By better understanding the negatives of acrylic roof coatings, our contractors can improve overall system performance, increase longevity, and avoid any potential problems.

Acrylic coatings blended today are far superior to the original formulations from long ago, but the problem of water ponding on a roof still remains. Acrylic coatings are water-based and will eventually begin to break down if exposed to ponding water for an extended period of time (see pictures below). Standing water for more than 48 hours over any acrylic roof coating will ultimately cause the system to fail.

While this won’t happen immediately, a complete system failure is most likely to occur within a couple of years. This water-based product simply cannot withstand ponding water. Eventually, the coating will become brittle and delaminate from the roof.

Better Alternatives for Flat Roof Substrates

The Ure-A-Sil Roof Restoration System

For most flat roofs, we recommend the Ure-A-Sil System. This hybrid system combines the strength and durability of urethane coatings with the flexibility and UV stability of silicone coatings. It’s hands-down the best roof coating system for ponding water situations.

Silicone coatings can fully withstand ponding water for an indefinite period of time. The Ure-A-Sil System, even after 10-12 years, is proven to resist moisture penetration. Even in areas of standing water, the silicone top coat will never show signs of degradation.

The Envir-O-Sil Roof Restoration System

Another great solution for flat roofs is the Envir-O-Sil System. This system utilizes low VOC, high-solids, silicone roof coatings making it the ideal solution for areas regulated by strict environmental standards. The Envir-O-Sil System provides outstanding UV protection and weatherability—all while having minimal impact on the environment.

Conclusion

At American WeatherStar, we will continue to champion the benefits of acrylic roof coatings, but only for roofs that drain properly. In fact, the majority of our acrylic coating systems are applied over sloped metal roofs. There are times when a standard flat roof is designed with sufficient drainage. In those situations, an acrylic system can be a perfectly effective solution.

To learn more about the negatives of acrylic roof coatings on flat roofs, click here to contact your American WeatherStar Field Representative.