Roofing contractors can choose from a full series of products and specifications that combine self-adhered membrane technology with the performance of fully adhered roofing systems.
Primary among these choices are self-adhering TPO (thermoplastic polyolefin) single-ply roof systems. These energy saving, reflective TPO roof membranes continue to be the fastest growing product segment among contractors in the low-slope market.
Self-adhered TPO roofing systems with welded seams reduce the number of steps required for the installation of the roof, so they offer the protection of adhesive securement with faster installation.
In addition, the factory-applied adhesives on self-adhered roofing membranes can significantly reduce application errors, as well as the equipment and storage concerns prevalent when using cold adhesives. Field-applied adhesives can be fussy — too much adhesive can damage the system, and too little can compromise the bond.
Another reason for the popularity of self-adhered systems is their use on non-metal decks, replacing the need for mechanical fastening, which requires considerable additional labor, time, materials and cost.
Both self-adhered SBS and TPO systems offer a number of advantages when roofing high-rise buildings with concrete decks where access, materials storage, and fastening issues often arise.
Another reason for the growth of self-adhered membranes lies in the fact that they also reduce or eliminate the need for supplemental cements and adhesives that often contain VOCs (volatile organic compounds). Driven by EPA (Environmental Protection Agency) mandates, many states have adopted more stringent clean air rules that effect many traditional adhesives. Unlike cold-applied mod-bit assemblies, self-adhered systems are virtually free of fumes and VOCs, meeting California’s strictest emission standards.
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On the basis of material costs alone, self-adhered roof membrane materials may appear more expensive than other products, but the savings in labor usually more than offsets the additional cost.
In the field of the roof, it takes no more than a few minutes to install a roll of membrane, which may vary depending on membrane type, from one square (100 square feet) of modified bitumen to 10 squares (1,000 square feet) with larger TPO rolls. Once the sheets are properly positioned, the applicator peels back the release liner to expose the adhesive backing and rolls in the membrane.
Self-adhered TPO can also save roofing contractors time and labor when installing perimeter cover strips. Instead of heat-welding the cover strip 13 mm (0.5 in.), the applicator can simply peel back the release paper and adhere a long strip of cover tape to the primed perimeter detail in one step.
Self-adhering membranes are not without some limitations. The Asphalt Roofing Manufacturers Association recommends temperatures must consistently be a minimum of 50 degrees Fahrenheit and rising for best results; the jobsite should also be free of dust and debris that may interfere with adhesion. Most manufacturers require the membranes be rolled in with a weighted roller to promote adhesion to the substrate.
Without question, self-adhesive technology, whether used in conjunction with multi-ply modified bitumen systems or single-ply TPO membranes, is addressing the needs of the market and assuming a prominent place as a core application method.