ARCHIVED - Canadian roofing leaders put NRC research to work
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December 03, 2008— Ottawa, Ontario
- For over a decade, NRC has helped many of Canada's top roofing manufacturers develop state-of-the-art roofing systems. Through an ongoing partnership with the roofing community, NRC research is reflected in commercial roofing installations from coast to coast. Recently, more than 70 technical professionals from Soprema Canada, a major Canadian roofing membrane manufacturer, visited NRC labs to understand ongoing research initiatives.
"Soprema manufactures roofing systems that account for more than 50 percent of the Canadian commercial roofing market," says Dr. Bas Baskaran, who leads the roofing systems group at the NRC Institute for Research in Construction (NRC-IRC) in Ottawa. "In the 1990s, Soprema asked us to evaluate various products. One of their top concerns was to be able to measure thermally induced stresses on the roofing membrane."
|Installation of a roofing system at NRC's Dynamic Roofing Facility.|
"For the last 15 years, we've acted as an extension of Soprema's R&D facility," notes Dr. Baskaran. "They come to us when they don't have the required equipment for specific test procedures."
In 1993, Soprema was just opening its own R&D facility in Drummondville, Quebec. "When we approached NRC, it was a win-win situation for both parties," says John Harquail, Soprema's marketing and communication manager. "Our partnership with NRC increases their capacity to conduct research projects to enhance the waterproofing performance of roofing systems."
In November 1994, NRC created the Special Interest Group for Dynamic Evaluation of Roofing Systems (SIGDERS), which includes Soprema and other industry partners. Led by NRC, SIGDERS has created new ways for testing and simulating the wind conditions that impact on flexible membrane roofs during hurricanes and other extreme weather events.
Testing the winds
Since roofs are constantly exposed to the elements, they are one of the first parts of a building to suffer damage during a hurricane. The low-slope roofs of hospitals, emergency shelters, fire stations and other critical buildings must be able to withstand the forces of persistent, high winds, as well as the extensive and destructive rains that accompany hurricanes. NRC researchers simulate high wind suction on roofing membranes in a special enclosed chamber, using a gust simulator to simulate wind fluctuations. This dynamic wind uplift test protocol was recently adopted by the Canadian Standards Association and published as a national standard (CSA #A 123.21-04), which is now being used by the construction industry.
A few years ago, Soprema began introducing fastener-free roofing systems. "Metal fasteners or screws are a common method used to keep roofs in place, says Dr. Baskaran. However, in Canada, they act as a "thermal bridge," causing heat loss or heat gain through the roof. Soprema has developed technologies for installing pre-fabricated waterproofing membranes using adhesives rather than fasteners, in order to minimize heat loss or gain.
"Once there is a path for heat or cold to get through a roof, moisture can accumulate, lowering the thermal value or causing some other degradation," explains Dr. Baskaran. "Getting rid of the fasteners is one way to help preserve the roof."
NRC and SIGDERS, along with the support of manufacturers such as Soprema, are now examining the thermal movements on roofs and the effects of wind uplift on fastener-free roofs. "At NRC, we can test pressures of up to 300 pounds per square foot — equivalent to 250 kilometre-per-hour winds — which covers most of the wind conditions in Canada," says Dr. Baskaran. "Using our testing facility, we can predict what will happen if a hurricane passes over a roof."
"This facility is the only one in the world that can test winds at these speeds," he concludes. "This facility helps Canadian manufacturers who want to evaluate their products' performance so they can penetrate U.S. markets — especially the east and southern coasts, which experience high wind conditions."
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