The strength of lumber joints depends on:
- the size of the glued area (if adhesives are used);
- the way in which one piece of lumber encases the other; and
- the accuracy of the joinery.
Note that end-grain lumber glues less well than lumber surfaces that run parallel with the wood grain.
The main types of lumber joint are:
- angle or cross lumber joints, in which the two pieces of lumber join at an angle—e.g. mortice and tenon, lapped joints, dovetail joints, and comb joints;
- widening joints, which widen a lumber board by adding a thin section parallel to it;
- lengthening joints, which extend the length of a lumber member; and
- hinge and “shutting” joints, which aim to form an air- or watertight seal.