Measurements of water vapour permeability of oriented strand boards

Oriented strand boards (OSB) are one of the most used elements in modern timber-based buildings. An important property is their permeability to water vapour. It commonly characterized by diffusion resistance factor ( μ -value). not a constant, but moisture-dependent function that often determined using cup method. However, results found literature have large variance. This paper presents carefully performed laboratory measurements Measurements were made at different sorption moisture contents OSB. The measured -values ranged from 40 for samples with high content 160 low content. values derive functions cover entire hygroscopic range. They can be hygrothermal modelling building envelopes containing