The need for a revised edition emerged in 2020 when FortisBC observed a growing number of retrofits involving larger and smaller multi-unit residential buildings. To support incentive programs for social housing retrofits, FortisBC required a resource that communicated the performance risks of adding insulation, particularly in attic roofs, under the region’s coastal conditions. BC Housing, the publisher of the guide, engaged RDH to update the 2016 version with expanded and timely content addressing these evolving retrofit challenges.
RDH’s technical team drew on findings from a 2019 BC Housing research project that examined moisture issues in new roof assemblies, even when built to code and best practices. While that study focused on new construction, our team supplemented it with a targeted literature review of resources specific to retrofitting. This integrated approach led to new guidance on avoiding condensation and mold risks in attic retrofits, which is an essential addition for energy retrofit programs across BC.
To develop the new section discussing condensation and mold risks in attic retrofits, our team used data gathered from a 2019 roofing research project conducted by RDH for BC . This research examined moisture-related issues that can occur in new roofs, even when they are constructed according to best practice guidelines. Since this research applied primarily to new construction, we also conducted a literature review of additional industry sources on retrofits and combined that information with our study results to develop improvement standards for a BC archetype.
The updated 2020 guide offers clear, illustrated procedures for improving the energy performance of wood-framed detached homes, semi-detached homes, and townhouses. Along with guidance on air sealing and insulating attics and roofs, it covers above-grade walls, basements, crawlspaces, floors, and key transition points. Additional content addresses window and door replacement, weatherization, and project planning, supported by step-by-step illustrations, practical checklists, and a glossary for field use.
This resource continues to serve as a cornerstone for FortisBC’s incentive programs, helping practitioners reduce energy consumption, lower utility costs, and mitigate performance risks during retrofit work.
Download the guide here: https://www.bchousing.org/publications/best-practices-air-sealing-insulation-retrofits.pdf
