Self-adhering single plies: an emerging technology

Single-ply membranes have become important players in the low-slope roofing market. Products such as EPDM and PVC have been used in the U.S. roofing industry since the late 1970s. TPO has been used as a roof membrane since 1991 and currently is the fastest-growing segment of the low-slope market, according to surveys conducted by NRCA and SPRI. Like all products, single-ply membranes have had their problems. However, they are considered dependable and competitive roof systems.

Many in the roofing industry believe fully adhered single-ply membrane roof systems are the best single-ply roof systems available. There are a number of reasons for this belief, including the following:

  • Fully adhered systems have exposed membranes, so it is easier to locate leaks and other membrane problems.
  • Unlike mechanically attached systems, which also are exposed membrane systems, there is little stress on the seams from wind and other loads because the seams are supported and reinforced by the substrate. This reduces the risk of seam failure and leaks.
  • Fully adhered systems work well on oddly shaped and steep-slope roofs because the adhesives do not slide and the membranes are lightweight, so gravity does not pose a big problem.
  • It is easy to design effective vapor-retarder systems, which is not true of, for example, mechanically attached systems.
  • Maybe most important, fully adhered systems have the best performance record during the years.

Review of NRCA's 2006-07 Low-slope Roofing Materials Guide, as well as membrane manufacturers' literature and Web sites, has revealed four manufacturers that produce self-adhering, or peel-and-stick, single-ply membrane products—three manufacture TPO membranes and one manufactures PVC membranes. General information about these products is shown in the figure.