For anyone interested in the state of TPO roofing, its future growth and expansion in residential and commercial roofing markets, it is important to know that TPO roofing is being actively discussed and evaluated by such reputable organizations as MRCA.
In 2010, at the 61st Annual MRCA Conference, there was a very important presentation by the panel on “TPO Long-Term Performance”. This panel addressed to the best their ability and expertise some of the serious concerns that have been raised in the roofing industry regarding the longevity and durability of TPO roofing membranes and reported failures of the membranes under certain climactic conditions. This information on TPO’s is particularly valuable if you are considering installing a TPO roofing membrane on your residential or commercial property.
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The TPO panel at the conference was moderated by MRCA’s technical advisor, Rene Dupuis of SRI Consultants Inc., and featured Helene Hardy Pierce of GAF Materials Corp., Dwayne Wacenske of Firestone Building Products, Tom Taylor of GAF Materials Corp., and Randall Ober of Carlisle SynTec. Panelists addressed the issue of high-temperature solar loading on TPO roofing products, reviewed field studies and ASTM standards.
Overall the panelists were in consensus over the fact that TPO roofing membranes do offer both performance and longevity that customers can depend on. For example, Hardy Pierce of GAF pointed out that many TPO roofs in the US are routinely approaching 20 years in service. She also cited statistics estimating that TPO accounted for about 25 percent of the U.S. commercial market in 2009-2010. Next, Wacenke of Firestone discussed the ASTM Standard for TPO and pointed out that TPO passed the durability tests that have been conducted including heat aging at an oven temperature of 240 degrees Fahrenheit for 28 days.
Then, Taylor of GAF addressed the fact that manufacturers are aware that exposure to UV rays was problematic for TPO membranes, however he claimed that heat actually was not the problem. For him and for his fellow reps of various US TPO manufacturers the real problem that could explain the issues that have been surfacing with many TPO roofs premature aging and failures was the fact that membranes were being installed in locations that manufacturers had not intended them for. He stated that one common denominator that was present in most failed TPO roofs was that the membranes were either near highly reflective surfaces or there was a buildup of dark dust and debris, which absorbs more sunlight and more heat.
Another factor that was contributing to membrane’s failures was the fact that installing black PV panels directly on TPO can bring roof temperatures to 180 degrees between the panels. Moreover, areas directly below the black edge of panels can reach sustained temperatures of 200 degrees. According to the panelists, TPO developers didn’t initially design the membranes for these temperatures and conditions. As a result, they conceded that it was necessary to have a more aggressive ASTM standard that would include an oven heat aging tests of TPO conducted at 275 degrees for a minimum of 8 weeks.
While much improvement with TPO’s chemical formulation still needs to be done for the membrane to live to its own standards, it is clear that TPO manufacturers are working hard to address the problems and to deliver a product they can stand behind. If you are planning to install a TPO roofing membrane, make sure to review the track record of a particular TPO manufacture you choose to work with. In general, err on the side of caution and go for TPO manufacturers that have been in the industry for at least 20 years.
Published date: September 24, 2012