| Abstract | Uncontrolled moisture accumulation in a building envelope reduces the structural integrity of its components through a combination of mechanical, chemical and biological degradation. Damage induced by moisture ingress includes rotting of wood studs and wood-based sheathing, as well as other detrimental effects such as efflorescence and spalling of masonry, and rusting of fastening mechanisms. Over the past decade, a significant number of low-rise wood-frame residential buildings have been plagued with water penetration problems related to uncontrolled moisture accumulation in the building envelope. In the majority of cases, the reported problems are in coastal areas such as lower mainland of BC, Maritime Provinces and eastern US. Effective moisture control is essential for an acceptable service life of building envelope. Effective moisture control implies both, minimising moisture ingress to prevent ingress of moisture into the inner most fabric of the wall assemblies, and redirection of moisture to the exterior. The principal objective is not to allow any component within the system to stay 'too wet' for 'too long'. The challenge would be to qualify and quantify what is considered "too wet" and "too long"? |
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