I’M BUILDING IN THE RAIN – WHAT HAPPENS IF WOOD GETS WET DURING CONSTRUCTION?
The wood will not be damaged by the water, but if the wood is too wet when it is enclosed into an assembly it will be at risk of decay. The National Building Code of Canada specifies that wood be at no more than 19% moisture content before enclosure – this is to provide a good safety margin against decay. How much water gets taken up by the wood depends on the circumstances. Wood does not absorb water very rapidly from surfaces parallel to its linear cells – in other words, rain falling on the face of lumber or a panel will generally only wet the surface of the piece, and this moisture can dry readily. However, water is taken up more quickly on the ends of pieces. If possible, ends of lumber and panels should be more carefully protected from water uptake. Any wood sitting in a pool of water will eventually absorb some of it through any face, and this is a particular problem for sill plates. The sooner a structure can be enclosed, and the roof can be installed, the better the chance for