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Perspectives A Quarterly Information Source from Benchmark, Inc. |
Single-ply Roof Systems: The Evolution Continues.Terrance R. Simmons, RRC Following is a discussion that will cover the position of single-ply roof systems within the roofing market over the past few years. It includes changes that have occurred among the manufacturers of single-ply membranes and roofing in general, new products and techniques, taking care of the single-ply roof, and a listing of resources for single-ply roofing systems. Market Position of Single-ply Roof Systems Over the past five years, the overall roofing market has remained relatively stable. The National Roofing Contractors Association (NRCA), Rosemont, IL, reports in their 1995 - 1996 Annual Market Survey that the total roofing market was $18.35 billion compared to $16.7 billion in 1990. The overall market dropped to $14.3 billion in 1992 but has seen steady growth since. Single-ply roof systems have seen their share of the overall roofing market slightly increase during the last five years. NRCA's Market Survey reported in 1990 that of the $11.6 billion commercial segment of the overall $16.7 billion market, 36.9% of new construction and 31.7% of reroofing projects utilized single-ply roof systems. That compares to the 1995 Market Survey that reports of the $13.2 billion commercial segment of the overall market, 40.5% of the new construction and 32.7% of reroofing projects were single-ply. While single-ply systems are not garnishing the leaps in growth experienced during the 1980s, their market presence has remained strong. Today, several varieties of single-ply systems are on the market. Some have now been available for almost two decades. Single-ply systems are categorized into two generic types: First, thermoplastic membranes are sheets where chemical crosslinking does not occur. Thermoplastic materials are seamed by either hot air or solvent welding of one sheet to the next creating a direct bond of the material. Second, thermoset membranes are those that chemically cross-link (i.e. cure). Most thermoset materials are seamed with an adhesive since the cured material cannot be chemically linked. The common formulations of these categories are as follows: Thermoplastic
Thermoset
Changes in the Manufacturing Arena While single-ply systems have held their position in the market, some of the producers and suppliers of these systems have experienced dramatic changes. Based on information contained in NRCA's Commercial Low-Slope Roofing Materials Guide, 1986 and 1996 editions, of the 10 suppliers who sold PVC systems in 1986, only three are still doing business in 1996. For EPDM systems, there were 20 suppliers in 1986. Today there are 18 suppliers of EPDM with only six of these doing business over that full 10 year period as the same entity. Another trend that developed a few years ago and has remained strong is the acquisition of smaller producers by larger roofing materials companies.
For the short term, this acquisition trend may continue. What needs to be monitored is the influence of these acquisitions on the roofing industry. For example, with Firestone's acquisition of Colonial Rubber Works, this has taken the number of producers of EPDM sheets down to two, Firestone and Carlisle SynTec Systems. Additionally, the following points need to be considered:
The answers to all of these questions are not clear at this point. It is important to be aware of these acquisitions so that changes in warranty coverage, support and products can be handled up front with the new ownership. New Products and Techniques While the manufacturers are not introducing new products at the pace they were a decade ago, new offerings are available. Ethylene Propylene (EP) is a blend of polypropylene and ethylenepropylene polymers. This membrane was offered to the market around 1991. It is marketed as either a reinforced or non-reinforced sheet. The manufacturers of this product tout its virtues of being rubber while also being a heat weldedable material like the thermoplastics. The product has not been on the market for an extensive period of time, so its performance track record is still indeterminate. As with all new products, only time will tell. Another development in the single-ply market is the advent of a second generation of adhesive seam tapes for use with EPDM systems. Driven by the volatile organic compound (VOC) emission issue, tapes are a means by which to reduce VOC emissions. Additionally, the manufacturers report that tapes can be applied faster than liquid adhesives. A joint industry-government study is underway at the National Institute of Standards and Technology (NIST) regarding the performance of adhesive seam tapes for EPDM. Initial results indicate that tape seams may have strengths above the average of butyl-based liquid-adhesive seams tested in earlier research work. (Reference the Proceedings of the 11th Conference on Roofing Technology, September 1995, available from NRCA, for additional information). The results of this research should be available in the near future, providing the industry with additional insight into the capabilities of this newer product. Taking care of your single-ply roof Periodic inspections of your roofs should be undertaken and routine maintenance conducted as a means of taking care of the investment made in the roofing system. For single-ply systems, a document is available for building owners to assist with the care and upkeep of the roof system - Manual of Roof Inspection, Maintenance, and Emergency Repair for Existing Single-Ply Roofing Systems, published jointly by the Single Ply Roofing Institute (SPRI) and NRCA. This document covers topics such as what to look for when conducting a roof inspection, causes of problems, owner-performed maintenance, and emergency repair procedures. Summary In closing, single-ply roof systems have now been in wide-spread use for almost two decades. These systems have enjoyed an increase in popularity during that time. However, time has tested some systems and some manufacturers. An evolution still continues in the market, as the manufacturers and suppliers work their way through mergers, acquisitions, buy-outs, and product problems and failures, and an evolution continues in the field as time and weather test the durability of these systems. Resources The following organizations offer publications that discuss single-ply roof systems in greater detail.
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