Without question, thermoplastic roof membranes have been fast-growing low-slope roofing products for more than a decade. Thermoplastic roof membranes come in different technologies, including TPO, PVC and PVC alloy. Long before TPO was introduced into North America, PVC membranes capitalized on several events during the 1970s to solidify its position. First, the oil embargo of 1973 inflated the price and restricted the availability of quality roofing asphalt. At the same time, high-energy costs increased demand for higher roof system insulation R-values. This began to make single-ply membranes more attractive. This attractiveness included their direct compatibility with polyisocyanurate insulation, also a growing product at the time.
In 1984, Ducker Research Inc. (now Ducker Worldwide) predicted single plies (including PVC and PVC alloys, EPDM, Hypalon® [CSPE] and CPE), would capture 25 percent of the low-slope market. By the middle of that year, single plies' share reached 35 percent of the roofs installed, and Ducker Research soon revised its year-end forecast.
TPO membranes also were introduced, and by 2006, the thermoplastic market share had grown. PVC and TPO together represented about 30 percent of the commercial roofing market, according to Ducker Research.
Five years ago, SPRI reported a great majority of the billions of square feet of single-ply membrane cumulatively sold in North America (including TPO and PVC) performed without issue.