Volume 31, Issue 4 (July 2003)
A New Facility to Simulate Simultaneous Wind and Thermal Effects on Roofing Systems
Roofing systems are exposed to wind pressures and thermal stresses. Through a North American roofing consortium (Special Interest Group for Dynamic Evaluation of Roofing Systems—SIGDERS) the National Research Council Canada fabricated a facility to evaluate roof assemblies under simultaneous wind and thermal effects. The overall objective of this paper is to present the commissioning process of the facility based on experimental investigations that were carried out on a single-ply roofing system with a PVC membrane. For this study, roofing system responses were measured under simulated simultaneous wind and heat/cold conditions. A systematic attempt also was made to quantify the system response and to characterize the membrane properties. This was performed on a cold-conditioned system as well as by subjecting the membrane samples to the same cold-conditioning program in a laboratory freezer. Membrane samples were characterized by mechanical and chemical methods. Comparison of laboratory-conditioned membranes and wind-tested systems revealed the effects of cold conditioning and wind loading. Neither the wind uplift nor the mechanical properties (tensile breaking strength, elongation at break, tear strength, and seam strength) nor the chemical properties (glass transition temperature and weight loss) were affected by the selected cold conditioning. Based on these findings, directives for further studies are presented for this ongoing project.