Abstract

Moisture sources in the building envelope are, in order of magnitude: rain penetration, moisture brought through air movement and moisture diffusion. As rain water impinges onto the wall and runs off the surface, water may seep into cracks and accumulate within the wood frame structure. Water can move by capillary action into wood-based components and the water vapor can also be diffusing through the structure. In the hygroscopic range, the theory has evolved considerably, and by the use of sorption curves, it is possible to explain the absorption of water in the vapor phase for a range of relative humidity (from 0 to 95% RH). However, liquid mass diffusivities of water for many Canadian wood species have not yet been investigated. The main objectives of this study are to quantify averaged values of diffusivities for a specific type of wood (jack pine), and to develop a transient modeling approach for liquid-phase water transport in wood considering the orthotropic effect of the wood structure and compare it to experimental results.