There are four main methods of joining lumber components:
Sometimes, these are used in combination—for example, a lumber joint can be glued and may be screwed as well. As with all fixings, it is necessary to be aware of the compatibility of the components. Some lumbers—such as oak, chestnut, redwood, and western red cedar—contain tannins, which attack ferrous metals; therefore, use lumber dowels or metal fastenings made of austenitic stainless steel. Tannic acid protects trees from insect and bacterial attack.