Building envelope essentials: The role of a water-resistive air barrier

 Demand for resilient WRABs

The CAN/ULC-S741 and CAN/ULC-S742 standards are interesting as they are much better at evaluating both a material and an assembly’s ability to perform to ultimate limits under more realistic environmental conditions than the ASTM test methods alone. CAN/ULC-S741 and CAN/ULC-S742 rely highly upon the ASTM methodology, but have improved upon the context in which it is performed. This can assist designers and specifiers in comparing systems in order to better understand and select the appropriate WRAB for their project. These improvements in standards are most welcomed, but if to be fully prepared to meet the challenges of a changing climate, it is important to ensure what is specified in design is achievable and verifiable where it matters most, which is, in the built environment.

To meet the challenges of tomorrow, there is a need to bring together quality specifications and standards with clearer building code requirements that insist upon verification of both the assembly and full building performance through a well-defined commissioning process. This may take great effort from all industries and influencers who are concerned with protecting the owner’s investment, but it is the appropriate choice to make. No one can assure what tomorrow will bring to the climate front, and the industry may be powerless to influence it; however, with a growing demand for resilient WRABs and structures, environments can be better prepared to face any environment.

 Notes

¹ Read more about the effects of climate change, www.climate.nasa.gov/effects.

² Read “BSD-018: The Building Enclosure,” John Straube, August 01, 2006.

³ Learn about the United Nation’s sustainable development goals, www.un.org/sustainabledevelopment

Author

Paul Johannesson, technical development manager at Siplast Inc., is a graduate of the University of Toronto, building science program, as well as the architectural design technology program at Humber College. With more than 30 years of experience in architectural, engineering, manufacturing, and distribution sectors, Johannesson is a registered certified engineering technologist (C.E.T.) with the Ontario Association of Certified Engineering Technicians and Technologists (OACETT) and a building science specialist (BSS) with the Building Science Specialist Board of Canada. He has also served as an adjunct professor at Humber College, teaching in architectural design technology and construction project management programs.