How Puncture Resistant Are Commercial Roofing Membranes?

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Contractors are careful on the roof, but accidents can happen. Heavy, sharp tools can get dropped. Stones, loose screws, or gravel can get stepped on and driven into the membrane. These things can happen during roof installation or when air-handling equipment, etc., gets installed or is worked on during routine maintenance. Some of these accidents can result in a puncture of the roof membrane. GAF set out to compare the two popular heat-weldable membranes, TPO and PVC, together with a range of substrates. So, which roofing materials will give you less worry about punctures? GAF’s research uncovered the answers.

Puncture resistance can happen in a few basic ways. Objects can impact at slow or fast speeds and be sharp or blunt. Single-ply membranes do not have the hard exterior surface or redundant layer, which are normally part of multi-ply systems, so they are sometimes perceived as less resistant to punctures. In an effort to shed some light on puncture resistance, GAF took a look at various TPO membranes from the major roofing manufacturers in 45-, 60-, and 80-mil thicknesses and 36- and 50-mil PVC samples.

GAF tested both low- and high-speed impacts and failure was defined as the force required to penetrate the top membrane layer to expose the scrim. In the low-speed test, thicker TPO was better, and fleece-back was also an improvement. No notable difference between manufacturers was found. PVC appears equivalent, except for the 36mil material. Being reinforced with a heavier weight fabric, it showed better performance, highlighting the importance of scrim in this low-speed test.

In the high-speed test, the TPO membranes again indicate that thicker is more puncture resistant with little differences between membranes of the same thickness from all manufacturers. The 50-mil PVC samples were slightly less puncture resistant than 45-mil TPO. One surprise was the poor result of the 36-mil PVC sample (even though it did well in the low-speed test), suggesting that the dense scrim in that membrane does not help resist a falling sharp object compared to a standard scrim. As with TPO, supported PVC is more puncture resistant.

It’s important to note that low-speed manual demonstrations done by slowly pushing a pointed object into a membrane are misleading. It’s best to look at approved test methods (rather than relying on a marketing gimmick) to show how roofing membranes hold up to punctures.

For more details on our tests and their results, see our recent article in Interface magazine.

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    • Thomas J Taylor, PhD

      Hi Jordan – thanks for reading the blog. Yes, there are many situations where membrane puncture resistance is a key requirement. For buildings with nearby tall trees, I would suggest using a cover board such as high density polyiso and a fully adhered membrane over it. Take a look at a more recent blog we have on impact resistance.

  1. Archana

    What does PVC membrane with 94% polymer mean. And does the PVC membrane expand and contract ? Does it retain its size back and how long does it take to return back

    • Thomas J Taylor, PhD

      I’m not sure where you saw the reference to 94% polymer. But, for regular PVC roofing membranes, the ASTM specification requires that PVC be at least 50% of the total polymer (i.e. the total plastic) that’s in the sheet. The rest will be the plasticizers (the materials that take the PVC from being rigid like a PVC pipe, and make it flexible), the pigments to give it the whiteness, biocides to limit mildew etc growth, and so on. There are two types of expansion/contraction. First, regular temperature changes like happen from day to night or summer to winter cause some thermal expansion/contraction. This is almost instantaneous. But also, during the first months after production and when the membrane is first installed, there can be some slight contraction otherwise known as shrinkage. This is not reversible.

    • Thomas J Taylor, PhD

      Our GAF ProBlog can be viewed and responded to on most platforms. But note that the responses are moderated to make sure they are appropriate. Replies of a commercial nature or that are offensive are blocked. At GAF we want all roof projects to be successful and education is a key to that. The ProBlog tries to provide education and timely information to the industry.

  2. steve

    A better question is what is the fade resistance of the dark green membrane in the photo and will the dark color which stays hotter longer affect a standard Tpo mbrane

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