II. Floor laying. - (A.) Floor laying is a branch of carpentry which, in some localities, is done almost entirely by specialists who can do a far greater amount than can the all-round man. Figure 5 shows the kinds of floors in most common use, the matched (a), and the square-edged (6). The former of these always should be blind nailed; that is, the nails should be driven into the edge as shown at c, with a nail set; the entire floor may then be laid with no nail heads showing.

This is the method by which the best floors are laid, though it is slower than the square-edged method, since the floor has to be laid one board at a time. Also it is a more expensive floor, as considerable lumber is used in making the tongue for matching the boards.

A piece of 3 1/2" matched flooring or ceiling is made from a board 3 1/2" wide, but its covering surface is only 3", as shown at a, Fig. 6. On account of the tendency of the grain of wood to straighten itself in drying, boards will frequently have "kinks" or short bends in them, due to cross-grained places; in order to straighten boards of this sort, it is often necessary, in matching them, to make their faces \" or \" less in width instead of only 1/2", and 1/4" less in thickness instead of \"', than the sawed dimensions, indicated in Fig. 6, which were based upon a straight board. Therefore it is customary to allow one quarter or one third of the floor area for waste in matching and in cutting out imperfections; while for a square-edged floor an allowance of one fifth or one fourth is sufficient, as there is no waste in matching. (See b, Fig. 6.) Usually it is not necessary that matched flooring should be nailed at every joist; an 8d floor nail every second or third joist is sufficient for narrow flooring; for wide material the nailings may have to be closer to hold the floor down properly. The best grades of factory matched flooring are usually bored along the edge to allow nails to be driven without splitting the piece. If these holes do not come over a joist, the nails will generally hold well enough if driven into the under floor only, as they enter the wood at such an angle.

Fig. 5. - Matched and Square-edged Flooring.

For a very nice floor it may be necessary to smooth, scrape, and sandpaper the boards after they are laid, though if the flooring has been well made at the mill, it will be enough for common work to smooth the few joints which may not have come down perfectly.

If paper is to be laid under the wearing floor, it should be laid from the side from which the flooring is laid, or else at right angles, so that the edges of the paper will not curl up and prevent the boards from coming to a joint.*

Fig. 6. - Waste in Flooring.

If a floor is to have a natural finish, the carpenter always should select wood of the same color. In no other place is thoroughly seasoned stock more necessary.

It is always best to lay a floor with as narrow boards as possible, as the shrinking effect of seasoning is thereby minimized; if wide boards are used, the cracks will be more open, and therefore more noticeable.

In laying matched flooring, much depends in getting a straight start. If the wearing floor is laid upon an underfloor, which is covered with sheathing paper, and if the base is cut down on top of it, as at a, Fig. 7, this is an easy thing to do, as the first two or three pieces may be nailed perfectly straight; but, if the base has been put on, as in b, the starting piece (c) should be carefully scribed to the base, the grooved edge being the one fitted. A straight piece must be selected for the first because a crooked one would make trouble in laying the next few boards. One with a bruised, grooved edge should be selected if there is such, as the bruise may be cut off in scribing, while it might destroy the piece for use elsewhere in the floor.

Fig. 7. - Laying the First Piece of Flooring.

If a quarter round, or shoe strip is to be used, as at d, Fig. 7, this fitting maybe dispensed with, and the starting piece laid straight. A strip of any kind at the joint between the base and the floor always seems to hide a bad joint, and it is rarely used upon the best work.

If a floor is to be hand smoothed, time may be saved by using care in selecting the grain, and by laying as many pieces as possible of the same grain together, then several more of grain running in the opposite direction. This can be done only in a general way, but it is good practice.

(B.) A square-edged floor should not be laid one board at a time, but a "bay" two or three feet in width, of the floor boards should be cut to the same length, and wedged so tightly that each joint will be perfect, as shown at d, Fig. 5. Enough nails are driven to hold the boards in place while the process is repeated until the entire floor is cut down; in doing this, the different bays of flooring should be cut to different lengths, breaking joints with the adjoining bay at least 32", or the distance between centers of two joists; this will prevent a straight joint from extending across the floor and will add to the stiffness of the building. It is best to select boards for each bay of the same aggregate width as the boards they join endways. Any small spaces left open on account of the material not exactly fitting can be filled in after the floor is nailed. In heavy buildings, it is quite a common custom to lay the flooring diagonally, to add rigidity to the structure.

When the boards are all cut and laid, marks should be made with a chalk line or pencil, by a straightedge, to indicate the exact location of the joists as a guide in driving nails. The young workman must learn to keep his left hand full of nails and one nail in the wood all of the time; with a little practice, one at a time may be picked out by the thumb and middle finger, and held for the first blow of the hammer.