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SIGDERS research results in two new tools for better understanding of roofing performance
The roofing industry now has two new tools at their disposal to investigate their products more accurately: a method to test the resistance of mechanically attached flexible membrane roofing systems to dynamic wind uplift, and a facility to test roofing systems under simultaneous dynamic wind and temperature conditions. These tools result from the completion of Phase II of the IRC-led SIGDERS consortium research project. SIGDERS stands for the Special Interest Group for Dynamic Evaluation of Roofing Systems.
IRC researchers developed the standardized test method using extensive wind tunnel testing, computer modelling and IRC's Dynamic Roofing Facility (DRF), which was designed and built during the first phase of the SIGDERS project. This work resulted in a developed load cycle that, for the first time, allows manufacturers to test their products in conditions that:
- mimic real wind effects;
- achieve failure modes observed under real conditions;
- identify the weakest link in the roof design;
- are easier to apply in the laboratory than existing tests;
- produce results quickly;
- conform to local standards; and
- account for variation in the building's internal pressure.
The developed dynamic load cycle has eight loading sequences. These loading sequences are grouped into five levels, which start with the lower pressures and increase gradually with each level. The loading cycle has the capacity to test roof samples subjected to simulated gusts of twice the design pressure.
SIGDERS NEWLY DEVELOPED LOAD CYCLE CAN IDENTIFY THE WEAKEST LINK IN A ROOFING SYSTEM DESIGN
Manufacturers will also gain information about the sustainability of roofing products in the North American climate from the latest upgrades to IRC's DRF. The addition of a thermal evaluation capacity makes the DRF the first facility in the world able to test roofing systems under simultaneous dynamic wind and temperature conditions. The temperatures available for conditioning range from the very low to the very high, in the range of -40C to +100C. This new capability will give unique insights into the relationship between temperature and wind resistance, and the resulting durability of roofing systems.
Currently, Phase III of the SIGDERS project is developing a design manual for roofing systems with flexible membranes. This manual will ensure that the results of the consortium's work are widely available and can be applied by the roofing community. In addition, the consortium will be submitting the new test method to the CSA for evaluation as a possible national standard.
Specific questions can be directed to Dr. Bas Baskaran at (613) 990-3616, fax (613) 954-3733, or e-mail bas.baskaran@nrc-cnrc.gc.ca.
SIGDERS membership
Led by IRC, SIGDERS-the Special Interest Group for Dynamic Evaluation of Roofing Systems-has been investigating the effects of wind on single-ply roofing (SPR) systems since 1994. Since its inception, the group's membership has grown steadily. The membership roster as of November 2001 includes:
Industry Associations
Canadian Roofing Contractors' Association
Canadian Sheet Steel Building Institute
Industrial Risk Insurers
National Roofing Contractors' Association
Roof Consultants Institute
Manufacturers
Atlas Roofing Corporation
Canadian General-Tower Ltd.
Carlisle SynTec Incorporated
GAF Materials Corporation
GenFlex Roofing Systems
Firestone Building Products Company
IKO Industries Ltd.
Johns Manville
Sarnafil
Soprema Canada
Stevens Roofing
Vicwest Steel
Building Owners
Canada Post Corporation
Department of National Defence
Public Works and Government Services Canada
