The boards in floors are seldom long enough to go right across the room.
In such a case the joint between the end of one board and the next is called the heading joint.
Headings should always fall upon joists, and break joint with one another in plan.
In this the ends of the boards simply butt against one another, similarly to the side joints in Fig. 292.
The ends of the boards are splayed to fit one another, as shown in Fig. 299.
Related and Tongued Heading is formed in the same way exactly as the joint shown in Fig. 2 94, and has the advantages mentioned at page 135.
Fig. 299. Splayed Heading.
In these the ends of the boards are cut into a number of sharp salient and re-entering notches, whose ridges are parallel to the surface of the floor. These notches fit one another, and form a tight joint.
Such joints are sometimes used in oak floors, but they are extremely troublesome and expensive to make, and the point nearest the surface of the floor is very liable to break away, even in hard wood.
Sometimes in very common work boards of unequal width are used, so that there are breaks in the longitudinal joints. This occurs chiefly when the floor is laid "folded," as described on page 139.
The usual practice is, however, to have the floor boards gauged to the same width, so that their longitudinal joints form straight lines from end to end.
Floor boards should be brought on to the ground prepared and planed, generally by machinery, as early as possible after the building is commenced, so that they may be thoroughly seasoned before they are required to be laid.
If not prepared by machinery, the boards should all be brought to the same width, have their edges shot, and be gauged to the same thickness with a fillister plane, which takes out a rebate on each side down to the gauge mark.1 They are then turned over, and trimmed down to the proper thickness at the points where they cross the joists.
The best floors are those laid with narrow boards (from batten widths down to strips of 3 inches or 4 inches wide), as the shrinkage in each is less, and the joints can be kept tighter.
The boards may with advantage be placed in position, and left a year thoroughly to season before being nailed down.
1 This operation is called fillistering.
However well seasoned they may be, they will always curl up a little after being touched with the plane.
Two boards are laid and nailed at a distance apart little less than the width of 3 or 4 boards. These are then put into the space, and forced home by laying a plank upon them, and jumping upon it (see Tig. 300).
The boards thus laid together are often of the same length, so that their heading joints fall into one line, and are not properly broken.
Known as "Victoria Floors." In very superior floors two layers of boards are frequently used. The lower layer consists of 3/4 inch deals carefully laid and nailed on to the joists in the usual way. When it is down, the grounds, joinery, skirtings, etc., are fixed, and the plastering completed. After which, the upper layer, consisting of narrow strips 1 or 1 1/4 inch thick, it may be of wainscot oak or of some superior wood, is fixed with dowelled or other secret-nailed joints.
The position of the nails, in the various forms of joint, is shown in the figures.
Fig. 300. Laying Folded Floor.
Flooring brads (Fig. 303) are generally used for securing the boards to the joists. They are fiat-sided nails, which are easily driven in parallel to the grain of the boards without danger of splitting the wood; their heads being parallel with the grain can be punched below the surface so as to admit of the floor being planed.
They hold better than clasp nails (Figs. 301, 302), and the heads of the latter disfigure the surface of the floor - clasp nails must however be used for edge or secret nailing - as brads would break under the cross strain brought upon them in that position. Holes must be bored for wrought clasp nails or they will split the wood in driving - the labour of boring is saved where cut nails are used.1
When the heads of the nails are concealed, as in Fig. 294, the floor is said to be " secret-nailed." This may be effected in the joints shown in Figs. 296, 297 by driving the nail obliquely through the edges of the boards, taking care to clear the tongue or feather.
Secret-nailing is sometimes advisable for polished oak floors, or when the boards are very narrow, as, in the latter case, there would otherwise be a great many nail-heads in the surface.
Occasionally, especially in oak floors and where boards may have to be removed to get at gas pipes, etc., the boards are screwed down. For oak floors the hole should be countersunk, or a piece taken out about 1/2 inch deep above the head of the screw and filled in afterwards with pieces of oak to match the floor; this is called "pelleting."