The Building Technology Resource
Plywood is a type of engineered wood made from thin sheets of wood, called plies or wood veneers. The layers are glued together, each with its grain at right angles for greater strength. There are usually an odd number of plies, as the symmetry makes the board less prone to warping. The adhesives used in [...]
Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It is composed of cells, and the cell walls are composed of microfibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%). In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a [...]
Oriented strand board, or OSB, or waferboard, or Sterling board (UK) or SmartPly (UK & Ireland) is an engineered wood product formed by layering strands (flakes) of wood in specific orientations. In appearance it may have a rough and variegated surface with the individual strips (around 2.5 by 15 cm (approx. 1 in by 6 [...]
Wood warping is a deviation from flatness as a result of stresses and shrinkage from the uneven drying of lumber. The types of wood warping include: bow : a warp along the length of the face crook: a warp along the length of the edge kink: a localized crook, often due to a knot cup: [...]
In ring-porous woods each season’s growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before. In the case of the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may [...]