The role of the building envelope research team in this project was to assess whether midrise wood-frame (LWF) and cross-laminated timber (CLT) building envelope solutions developed by the fire research team to meet the fire provisions of the National Building Code (NBC) 2010 Part 3 Fire Protection, would also meet the NBC Part 5 Environmental Separation requirements relating to the protection of the building envelope from excessive moisture and water accumulation. As well, these wood-based mid-rise envelope solutions were to be assessed for their ability to meet Part 3 Building Envelope of the National Energy Code for Buildings (NECB) 2011. Requirements relating to heat, air, moisture, and precipitation (HAMP) control by the building envelope are included in Part 5 Environmental Separation of the NBC 2010. Part 5 addresses all building types and occupancies referred to in Part 3, but unlike requirements for fire protection, this section of the code was written more recently and is generic, including requirements that are more objective-oriented rather than prescriptive requirements pegged to specific constructions systems. The investigated methodologies developed and adapted for this study took those code characteristics into account.
The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of massive timber walls on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9.4 for 31 consecutive years of the 15 realizations of the modeled historical (1986–2016) and future (2062–2092) climates of five cities located across Canada. For all cities, water penetration in the wall assembly was assumed to be 1% wind-driven rain, and the air changes per hour in the drainage cavity was assumed to be 10. The mold growth index on the outer layer of the cross-laminated timber panel was used to compare the moisture performance for the historical and future periods. The simulation results showed that the risk of mold growth would increase in all the cities considered. However, the relative change varied from city to city. In the cities of Ottawa, Calgary and Winnipeg, the relative change in the mold growth index was higher than in the cities of Vancouver and St. John’s. For Vancouver and St. John’s, and under the assumptions used for these simulations, the risk was already higher under the historical period. This means that the mass timber walls in these two cities could not withstand a water penetration rate of 1% wind-driven rain, as used in the simulations, with a drainage cavity of 19 mm and an air changes per hour value of 10. Additional wall designs will be explored in respect to the moisture performance, and the results of these studies will be reported in a future publication. View Full-Text
The objectives of this work include the following:
· Conduct a series of water entry tests over a wide range of simulated wind pressure and WDR loads to measure the water entry rate passing the cladding through deficiencies located in a fibre cement cladding system; A1-100035-03.3 2
· Use the test results to develop correlations for determining the percentage of water entry rate through deficiencies as a function of pressure difference across the assembly and water spray rate onto the cladding surface;
· Analyze the water entry data for the NBC stucco cladding for high wind pressures obtained in a previous study (see  for more details) and applicable for mid-rise and taller buildings and thereafter develop a correlation to determine the percentage of water entry rate as a function of wind pressure and WDR for absorptive claddings.
The role of the Building Envelope team in this project is to assess whether alternate wood-based building envelope solutions developed by the Fire Team to meet the fire provisions of NBC 2010, also meet NBC Part 5 requirements relating to the protection of the building envelope from long term degradation due to uncontrolled heat, air, moisture and precipitation (HAMP) ingress into the building envelope of mid-rise buildings.
In a process of consultations with stakeholders, including the Canadian Wood Council (CWC), FPInnovations, and consultations with NRC’s Fire and Acoustics teams, specifications were developed for 2.44 m x 2.44 m wall specimens that would be investigated for hygrothermal performance.