During the past 20 years, TPO has grown to become one of the
most commonly used low-slope roof membranes. Factors contributing
to this growth include reflectance, ease of installation and
overall value. But as the material has gained in popularity, there
have been some questions about its long-term performance. Although
the material has not suffered from systemic problems, manufacturers
have seen intermittent membrane issues.
Studies have been conducted since 2000 to examine TPO's
long-term performance. For example, the Western States Roofing
Contractors Association (WSRCA) conducted an in-situ research and
testing program of 60-mil-thick TPO membranes from four
manufacturers. The test roof systems were installed during 2000-01
in four climate regions throughout western North America. Based on
regular sampling and testing, all test roof systems performed well.
There were no issues with seam integrity, membrane tightening or
overall watertightness. One membrane in Las Vegas had some cracking
that was associated with a sharp crease created during the original
installation. That same membrane also exhibited some micro-cracking
and crazing in a limited section. It can be concluded the high
solar irradiance (heat and light), possibly in combination with a
less robust formulation, led to this development.
A European study examined three TPO roof systems five and 10
years after installation. As with the WSRCA study, essentially no
membrane thickness change was observed. Also, all roof systems were
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