Sensitivity analysis of hygrothermal performance of wood framed wall assembly under different climatic conditions: the impact of cladding properties

One of the parameters that influences the moisture performance of the wood framed wall assembly is the material properties of exterior cladding. The uncertainties of its properties, would result in a range of wall performance. The objective of this study was to investigate the impact of uncertainties in cladding material properties on moisture performance of wood framed wall assembly under different climatic conditions. A wood framed (2×6 wood stud) wall with exterior brick cladding was simulated assuming 1% rain leakage deposited on the exterior side of sheathing membrane. A parametric study was carried out to analyze the impact of the cladding properties on the moisture response of OSB. The simulations were conducted in five different cities located in different climate zones across Canada. The aim was to identify the most influential cladding property on the moisture response of OSB, i.e., mould growth index and moisture content, to the varying cladding properties under different climatic conditions i.e., different cities under historical and future conditions. In general, it was found that liquid diffusivity is the parameter that has the most influence on moisture response of OSB in all the five cities. Also, the significance of this influence varies depending on the climatic conditions.

Numerical Evaluation of the Non-Isothermal Method for Determination of Moisture Diffusivity

A non-isothermal (linearly increasing temperature) procedure was used to determine the moisture diffusivity in mass transfer as a function of temperature with the complex optimization method. The effects of heating rate and experimental errors on the prediction accuracy of the parameters in Arrhenius equation were evaluated through pseudo-experimental data randomly generated on the basis of simulation results. An optimum heating rate of 0.01 K/s was found at which the experimental error less than 15% has negligible effect on calculated liquid diffusivity.