Building energy regulations have been changing quite quickly across Canada to meet the mandates of governments to reduce energy consumption and greenhouse gas emissions. Canadian model energy codes including the National Building Code of Canada (NBCC)—9.36. Energy Efficiency and the National Energy Code of Canada for Buildings (NECB) have been incrementally raising energy efficiency requirements, moving towards being net-zero energy ready. The Government of British Columbia enacted the Energy Step Code in 2017, so new construction will reach net-zero energy ready by 2032. The Canadian Home Builders Association (CHBA) has recently launched its Net Zero Home Labelling Program, providing two-tiered technical requirements for Net Zero and Net Zero Ready Homes.
Most of the Canadian energy codes and programs take an “envelope first” approach, as reducing heat transmission and air leakage through the building envelope is the most effective method to minimize energy loss. For example, the City of Vancouver requires RSI 3.85 (R22) effective for walls of residential buildings up to six storeys and mandatory airtightness testing.
Industrialized construction brings a revolution to the construction sector by mass producing panelized assemblies and modular units, which are able to provide higher levels of thermal insulation and airtightness, along with improved construction quality and efficiency, and a solution to labour shortages in the construction industry.
This document has been developed to facilitate industrialized construction for wood-based building envelopes (exterior wall, roof) to meet increased energy efficiency requirements.
Mass timber and CLT construction offers many advantages, such as enhanced modularity, reduced construction schedules, improved thermal performance, and material sustainability. However, mass timber’s propensity to absorb moisture from the environment and the relative vapor impermeability of CLT panels introduces unique challenges when incorporated with the building enclosure. These challenges should be considered during design and construction phases to ensure long-term performance.
The VaproShield Mass Timber Building Enclosure Design Guideline covers the best practices for the design and construction of high-performance CLT wall and roof assemblies. RDH is the principal author and editor of the guide and within its capacity, we do not purport to endorse any specific material or technical matter within this guide.