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Roofing membrane based on Elvaloy® KEE solves time, budget problems

160,000-ft2 fully adhered Tri-Polymer FB® thermoplastic membrane, made by Flex Membrane International, Inc., was installed directly on top of existing roof at Ohio factory, providing a cost-effective reroofing solution.

Application over old foam roofing delivers multiple benefits

The owner of an Ohio packaging products factory building had a 160,000-ft2, sprayed urethane foam roof that began to leak in the winter. Should the foam be patched, or the roof replaced?

The answer: both of the above.

Mr. Straily, Vice-President of Architectural Consulting Services International, Inc., Chicago, Ill., coordinated the project. Time and budget were both limited.

After exploring many possibilities, Straily found the resources that let him take the unusual step of repairing and retaining the old foam roofing for its insulative value and re-roofing directly over it with a fully adhered thermoplastic membrane. This was the most cost-effective of several solutions, all others involving removal of the old foam, a step that would have cost up to 40 percent more.

Roofing material supplier a key to success

"We found a roofing materials manufacturer who had experience in this kind of re-roofing, who offered a single-ply membrane with all the right properties," Straily said.

His resource was Flex Membrane International, of Morgantown, Pa.

"They showed us proof of the pudding - a very successful re-roofing over foam project performed by a roofing contractor they worked with. Their membrane was Tri-Polymer FB, a proprietary adhered flexible sheet. Tri-Polymer FB has a molecularly-bonded polyester-felt backing that made full adherence practical, even in winter, using Flex Membrane's Flex 0032 cold adhesive." Tri-Polymer FB is formulated with DuPont Elvaloy® ketone ethylene ester resin.

"Tri-Polymer FB with Elvaloy® offered the toughness, flexibility, and resistance to harsh weather, oils, chemicals and UV light that we needed for this application," said Straily. "And we got terrific assistance from Flex Membrane and their installation contractor, Advanced Roofing, Inc., of Newtown, Pa. Even though we had a full-time quality control person on that job, Flex Membrane had their own people there a lot, too, monitoring the placement. I was impressed with that."

Cold weather no problem

The reroofing procedure called for fully cleaning the existing surface, leveling peaks and valleys, and patching with compatible insulation. Then, the Tri-Polymer FB was unrolled, adhered, and its seams were sealed.

Winter temperatures posed no installation problems, due to the cold-temperature flexibility of Tri-Polymer FB.

The high molecular weight of DuPont™ Elvaloy® versus liquid plasticizers helps maintain flexibility after long term exposure. The heat welded seams made it possible to seal off each day's work, leaving it watertight.

The roof was completed on time and on estimate.

An added benefit is the white color of Flex Membrane Tri-Polymer FB. By reflecting sunlight, it decreases heat absorption into the underlying foam insulation.

"We have a very satisfied customer," Straily concluded.

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