Durability of energy efficient wooden buildings: a building physical point of view

IRG/WP 17-40812

S Roels, J Langmans

The drive for more energy efficient and sustainable buildings resulted in an increased popularity of wooden buildings, even in countries with a masonry tradition. Often guidelines and prescriptions then are copied from other countries. Different climatic boundary conditions and tradition of finishing, though, do require different moisture tolerance criteria. This is clearly the case for water vapour related damage. The current paper evaluates the durability of wood constructions from a building physical point of view. Focus is on moisture risks due to the combined heat, air and moisture transport trough wooden building components. Starting from the steady state analysis of pure vapour diffusion across a building component, the complex problem is stepwise analysed. The effect of hygric buffering in the wooden elements, different moisture sources and the impact of air transfer on the moisture tolerance are studied. Applications are shown for two types of components: the traditional lightweight walls as applied in platform framing and the more recent Cross Laminated Timber, which becomes increasingly popular as alternative for traditional framing.

Keywords: air tightness, vapour diffusion, interstitial condensation, platform framing, cross laminated timber

Conference: 17-06-04/08 Ghent, Belgium

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