Wood is a ligneous material grown by a living organism within a natural ecosystem. Tree growth depends on sunlight, the nature of the terrain, altitude, ambient temperature and climate. Sapwood thickness, annual growth rings, density and wood grain are all indicators of tree growth, and are instrumental in determining wood quality. Wood is a naturally environmentally friendly, recyclable and renewable product that can be used as a source of energy production.
Knots, veins, checks, splits, colour variations, dimensional distortions. None of these features lessen wood strength or durability. Wood is hygroscopic material, which means that its moisture content can increase or decrease with the temperature and humidity of the surrounding air in relation to weather conditions (sun, morning dew, inclement weather). These parameters obviously lead to variations in wood dimensions such as distortions, shrinkage, swelling and splits that depend on the species and the direction of the wood grain (axial, radial, and tangential).
However, there are a several processes available that are designed to limit these distortions. Drying timber to a moisture content of 12-18% significantly reduces dimensional variations. Timber treatment improves wood durability while the use of suitable products, particularly for external usage, prevents any colour changes or wood greying. Lastly, it is essential to fully comply with the standards described in the unified technical documents (DTU) that define how wood is to be used according to its natural features.
DTU 31.2 construction de maisons et bâtiments à ossature en bois
DTU 41.2 Revêtements extérieurs en bois pour les bardages
DTU 51.4 pour les terrasses en bois