71. Carpentry, as applied to house building, relates to the construction of the rough timber framework of the building in all its parts, from the foundation to the roof. In buildings which are partly constructed of stone or other material outside the carpenter's province, the carpenter is usually called upon to furnish, and generally to set, all centers, templets, wood lintels, etc. that may be required for arches, square openings, and angles.

72. Buildings constructed entirely of wood, above the foundations, may be divided into two general classes; viz., braced-frame and balloon-frame structures.

A braced-frame building is one in which each piece of the structure is carefully fitted and fastened to every other piece it comes in contact with, and the whole skeleton is thereby made stiff and secure before any of the covering material is applied.

A balloon frame, on the contrary, is one in which the timbers are simply nailed together; it depends, therefore, entirely upon the sheathing, or outer covering, for strength and security.

73. The former method is the one used in ancient times, and had its origin when all nails, bolts, and iron straps were made by hand, and required more labor to produce them than the cutting of mortises, or the halving of joints. With the advent of machine-cut nails came the balloon frame, which, though it may be a somewhat flimsy affair in itself, is, after the sheathing is on, much stronger and stiffer than the regular, or braced frame, and costs about half the money.

There are still, however, classes of buildings where the balloon frame is hardly suitable, and there are also instances in balloon framing where the joints require close and accurate fitting. To effect the best construction in a building, therefore, requires not only a knowledge of the kind of material best suited to the place and purpose, but also a knowledge of the proper size or sectional area of each piece, to withstand the strain that may come upon it, and the proportions of its dimensions to give the required area and at the same time suit the position in which it is to be placed.

74. The fitting together of these several pieces of the structure demands a knowledge of the proper kind of joint required in each particular case; an understanding of the conditions likely to arise which would tend to render the joint more or less ineffectual, such as shrinkage, dry rot, or warping; and the ability to compensate or prevent any evil results which such conditions would entail.