Recent research in the field of assessment of hygrothermal response has focused on either laboratory experimentation or modelling, but less work has been reported in which both aspects are combined. Such type of studies can potentially offer useful information regarding the benchmarking of models and related methods to assess hygrothermal performance of wall assemblies.
This report documents the experimental results of a benchmark experiment that was designed to allow benchmarking of stud drying predicted by NRC’s an advanced hygrothermal computer model called hygIRC, when subjected to nominally steady-state environmental conditions. hygIRC uses hygrothermal properties of materials derived from tests on small-scale specimens undertaken in the laboratory. The drying rates of wall assembly featuring wet studs that result from moisture accumulated during the framing stage of a 5 or 6 storey building. The drying rate of those studs was assessed in an experiment undertaken in a controlled laboratory setting. The results were subsequently used to help benchmark hygIRC reported under separate cover.
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 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.