Although there are a great many different kinds of trees growing in different parts of the world, only a comparatively small number of them yield wood which is used to any great extent in building work. These differ very much among themselves, each variety possessing certain characteristics which render it especially suitable for use in one part of a building, while the same peculiarities of growth or of texture may make it unfit for use in another.

For use in places where the timber must be partly buried in the ground a wood is required which will be able to withstand the deteriorating effects of contact with the earth, and for this purpose chestnut, white cedar, cypress, redwood, or locust may be used.

For light framing is needed a cheap, light wood, as free as possible from structural defects, such as knots and shakes, and one which can be readily obtained in fairly long, straight pieces. Spruce, yellow pine, white pine, and hemlock all satisfy these requirements fairly well, spruce being perhaps a little better than the others, and more popular.

For heavy framing, such as trusses, girders, and posts, a timber is needed which is strong, and which can be obtained in large, long pieces. Georgia pine, Oregon pine, and white oak may all be used for such work, and also Norway pine and Canadian red pine. White oak is the timber which was always used for framing in the old days, but is too expensive to be used with profit for such work now. The timber most commonly used today is the Georgia pine.

A wood which can be easily worked and which will also be able to withstand the deteriorating effects of the weather is in demand for the outside finish. White pine is usually selected for this purpose, although cypress and redwood are also suitable and are used to some extent. The same woods are used for shingles, clapboards, and siding, with the addition of cedar and spruce for shingles, and Oregon pine and spruce for siding.

For the interior finish is chosen a wood which will give a pleasing appearance when finished and which will take a high polish, while for floors, hardness, and resistance to wear are the additional requirements. For floors, oak, hard pine, maple, and birch are good, while for the remainder of the interior finish white pine, cypress, and redwood for painting, or any of the hard woods such as ash, cherry, oak, walnut, or mahogany, may be selected.

Some of the more important varieties of timber used in Carpentry will now be mentioned, and a brief description of each variety will be given in order to convey an idea of their characteristics and the part of the world from which they come.