New Design Procedure for Wind Uplift Resistance of Architectural Metal Roofing Systems

Currently, there are no Canadian national guidelines for the wind uplift resistance of architectural metal roof systems. Thus, it is difficult to judge their suitability and performance based on a common standard. Given the increasing use of metal roofs, it has been determined that there is a need for the development of a design guide, that would be applicable to all regions of Canada. Metal roofs can be classified into two groups: Structural and architectural. This paper focuses on the wind uplift performance of architectural metal roof systems. Several parameters influence the wind uplift performance of the architectural metal roofs. This study finds that air leakage of the structural deck is one of the significant factors that influences the wind uplift performance. This is based on experimental investigations carried out at the Dynamic Roofing Facility of the National Research Council of Canada, using the Special Interest Group on Dynamic Evaluation of Roofing System dynamic wind test protocol. Architectural roofing panels with three different types of commonly used, seam-interlocking mechanisms (joint details) were investigated. It has been noted that the resistance to wind uplift pressure increases dramatically as the air leakage ratio decreases. A modeling method is also described which quantifies system response by simulating the wind gusts over roof specimens with different leakage ratios that can represent field assemblies. The 1995 National Building Code of Canada was utilized for the estimation of the wind-induced loads and the present study provided extensive experimental data for various systems with each type of seam detail. Based on this analysis, a simplified design procedure was developed. The simplified procedure is presented through case studies of metal roof assemblies located in the Canadian provinces of British Columbia, Ontario, and Quebec.