Adaptation of Low-Slope Roof Assemblies against Projected Climate Severities: Evaluation of a New Standard

3:05pm – 4:05pm

Sathya Ramachandran, Bruno Bernard

Knowledge Level: Intermediate
Credits: This session has been approved for 1.0 IIBEC CEH. | This session has been approved for 1.0 AIA LU/Elective. | 1 hour (60 min) of Education is eligible for 1 BSS Credit | 1 OAA Core Learning Hour | Session may qualify for PEEK CPD.
Session Topics(s): Roofing: R, Sustainability/Resilience: SUS, Case Studies: CST

Learning Objectives
At the end of this session, the attendee will be able to:

• Recognize the designer’s responsibility and means to include the project-specific wind uplift requirements for low-slope roofs.
• Describe existing challenges in meeting the current building code in resisting wind uplift and the required due diligence.
• Explain the CSA A123.26 standard.
• Discuss the potential effect of the new CSA A123.26 standard on the industry.

Description
The Ontario Building Code requires low-slope roof assemblies to withstand dynamic wind uplift according to the CSA A123.21 standard. This has had a major impact on the industry, obliging manufacturers to design, test, and determine the performance of complete roof assemblies. However, a recent project demonstrated a worst-case scenario: a series of errors involving a lack of site-specific wind values in the design specification, use of alternative methods of compliance presented by the manufacturer that were questionable, and poor quality of material handling and workmanship by the roofer during construction resulted in failure after strong wind events. As the industry tries to cope with these current requirements, the effects of climate change expose the built environment to more severe environmental stressors than what the code prescribes. Extreme weather events—including high wind speeds, intense rainstorms, heavy snowfalls, extended heat waves, and other stressors—are becoming more frequent and powerful. This session will discuss CSA A123.26, an optional standard that builds on CSA A123.21 in addressing the impacts of projected wind extremes and heavy rainfall. This presentation will also explore an evaluation of the CSA A123.26, which revealed some valuable lessons.

Presenter/Author

Sathya Ramachandran, Architect, OAA, MRAIC, BArch, MASc

Director – Building Science
EXP Services Inc.

Sathya Ramachandran has 24 years of experience in building science consulting and research, with a focus on such high-performance metrics as durability, resilience, energy conservation, and occupant comfort of building envelope assemblies. He has provided consulting services for various building types across North America and has advanced education in building science. He has strong knowledge, experience, and attention to detail in the areas of building science principles, material composition, regulations, different assemblies, and components. He is a voting member of the ASTM International E06 Committee for Performance of Buildings.
 

Bruno Bernard

Project Manager – Roof Testing Laboratory
EXP Services Inc.

Over his 30-year career, Bruno Bernard has developed an in-depth knowledge of roofing materials and their behaviour. Since 2016, he has headed the EXP roofing testing laboratory, the only laboratory recognized by UL DAP in Canada for the CSA A123.21 standard (Standard Test Method for Dynamic Wind Uplift Resistance of Membrane Roofing Systems). His duties include laboratory testing, in situ testing, and consulting expertise. He sits on the SIGDERS (Special Interest Group for the Dynamic Evaluation of Roofing System) committee and other related task groups.