Renewal Strategies for Highly Insulated Low-Slope Ventilated Wood-Framed Roofs in Cool Marine Climates (Canadian Building Enclosure Symposium)

Roof ventilation requirements are firmly established for residential wood-framed buildings, with ventilation commonly considered beneficial for providing drying, reducing cooling loads, minimizing ice dams, and extending the service life of roof materials by reducing surface temperatures. However, growing evidence of mold growth, moisture accumulation, and deterioration of the low-sloped wood-frame roofs in the pacific-northwest has initiated an ongoing debate regarding mandatory venting requirements. Of particular interest is how to improve durability of roof assemblies as part of renewals work, but current guidance for the design, construction, and renewal of roof assemblies is primarily anecdotal.

This presentation will highlight the findings of a significant research study and subsequent design guideline development conducted in British Columbia, Canada. This study and guide development includes a survey of roof conditions during renewals, monitoring and testing, hygrothermal and energy simulations, and an industry guide. The presentation will identify key factors impacting the observed performance of these roof assemblies, and the development of design solutions. The potential benefits of adding insulation above the roof deck, sealing of roof vents, and increasing airtightness will be presented.

Patrick Roppel, PEng

Morrison Hershfield Limited, Vancouver, BC, Canada

Patrick is a Principal, Building Science Specialist, and manages the Building Performance Analysis department at Morrison Hershfeld. With over 15 years of consulting experience related to building science and building envelope energy eficiency, Patrick’s focus in recent years has been providing tools and guidance to help practitioners make practical design decisions related to constructability, thermal, structural, energy, and hygrothermal performance.

Lorne Ricketts, PEng

RDH Building Sciences, Inc., Burnaby, BC, Canada

Lorne Ricketts is a Principal and Building Science Specialist with RDH Building Science Inc. specializing in new construction, investigation, and research work with typical projects including designing building enclosure systems, hygrothermal and thermal analysis, and testing and monitoring of building performance. In addition to his work with RDH, Lorne also passes on his knowledge to the next generation of engineers as an Adjunct Professor at the University of British Columbia where he teaches building science in the Department of Civil Engineering.