The Largest, Independent Performance Study
Given the roofing system’s rising popularity, manufacturer GAF set out on the largest ever independent TPO study to debunk some myths and exaggerated claims about the roofing system as well as learn more about it. GAF utilized Structural Research Inc., a highly respected laboratory, to perform the largest, independent performance study of the four major U.S. TPO brands. SRI conducted a variety of ASTM physical property testing including thickness above scrim and weld strength which showed mostly equal performance among the brands. It wasn’t until accelerated aging using ASTM heat aging, weathering, and weigh loss tests-associated with long-term membrane performance- were conducted that the various TPOs exhibited significant differences.(The four brands tested on were GAF EverGuard Extreme® TPO (50 and 60 mil), GAF EverGuard® TPO (60 mil), Carlisle Sure-Weld® TPO with OctaGuard XT™ (60 mil), Johns Manville TPO (60 mil), and Firestone UltraPly™ TPO (60 mil).)
The study came up with four key findings. First, all the brands tested not only met, but exceeded minimum ASTM D-6878 standards. While there were clear variations in major physical characteristics (overall thickness, thickness over scrim, and weld strength) of each brand, no brand was clearly or significantly better than any other in these tests. However, their second finding concluded that there were substantial differences between brands in accelerated aging tests. This method is one of the most important indicators of how long a TPO membrane will last. The top performing class were GAF EverGuard Extreme® (60mil) and EverGuard Extreme® (50mil), both of which had no visible deficiencies for over 190 days. In second place were GAF EverGuard ® TPO and Firestone TPO, which failed at 112 days and 105 days, respectively. The third best performing membranes were Carlisle and Johns Manville, which failed at 77 and 70 days. The third finding found that there were even more significant differences between the brands in the amount of weight lost during accelerated aging test. During the ASTM accelerated aging test (D573 @ 275º F), SRI recorded noticeable differences. Weight loss is important because it can lead to erosion and membrane failure. Once the membrane has experiences 1.5% weight loss, degradation occurred rapidly and the membranes were considered to have failed. The ranking among the brands was the same as in the last finding. Lastly, there was surprising variation in the consistency of membranes produced by each brand. It is logical to think that membranes manufactured by a single manufacturer should be relatively consistent from one production run (or plant) to another. However, the study found that some brands perform much more consistently than others. The brands that showed the greatest consistency of production were GAF, Firestone, and Johns Manville.
What Does All This Mean?
The heat aging test includes bending over the sample over a 3” mandrel and inspecting it with a 7x eye piece. If there is cracking found, the sample is considered to have failed. The picture to the right shows a roof that has failed due to cracking of the TPO. While looking for cracking, the SRI also weighed each sample. Once the sample lost over 1.5% weight, it was deemed to have crossed a threshold where it is more unstable and therefore susceptible to cracking and/or erosion. Just as was the case with cracking, the reason that weight loss is an excellent indicator of TPO performance is that it can lead to erosion. The picture to the left shows a failed roof where the cause was that the weathering layer had eroded to the scrim. A fundamental takeaway to take from this is that at the end of the day, it doesn’t matter which failure happens first ( cracking or weight loss) because failure is failure. The data shows that in terms of cracking or weight loss, the best performing TPO membranes are GAF EverGuard Extreme® (60mil) and EverGuard Extreme® (50mil). The second best were GAF EverGuard® TPO and Firestone TPO, and in third place came Carlisle and Johns Manville. As a closing remark, though TPO has a proven record of performance without systematic failure, there are significant differences among membrane brands and GAF is leading the industry with its EverGuard Extreme® and EverGuard ® product lines. Congratulations GAF! We are proud to be trusted Master Elite roofers with such a reputable manufacturer.
Here at Chase Construction North West Inc., we have many years of experience in TPO roofing. Below is a picture of a recent job we did utilizing this innovative and reliable roofing system.
We have worked with GAF products for over 13 years and have earned their coveted Master Elite® status that only 2% of roofers in the United States hold. Call us with your roofing needs today Puget Sound! We provide services in King County and Pierce County, along with major cities such as Seattle, Tacoma, Puyallup, Federal Way, Renton, Auburn, Des Moines and all of the surrounding cities. Contact us today by filling out our free estimate form or calling us at 253-445-8950.
Check out this video of our crew installing a TPO roofing system in Seattle, WA!