Flooring is the covering of the naked framing, and consists of one or other of the many different kinds of floor boards from 1 to 1 1/2 inch in thickness, nailed (on each of their edges) on to each of the bridging joists in either single, double, or framed floors.
The different kinds of joints for flooring boards (which should always be rebated or grooved so that a greater thickness of floor-board is left on the top side where it will be worn) are as follows: -
Straight or plain jointed(fig. 300), in which the joint of each board is straight and plain.
Grooved and tongued, where one edge of the board has a tongue and the other a groove (fig. .301).
Grooved and tongued with hoop-iron tongues, in which both edges of the board are grooved and an iron tongue inserted, half in each board (fig. 302).
Rebated, with the edge of each board rebated out alternately top and bottom (fig. 303).
Rebated, grooved, and tongued (fig. 304), a combination of figs. 301 and 303.
Rebated and filleted, in which each board is rebated out on one face each side, and a loose fillet is laid on the joists and overlapped by the rebate on each board (vide fig. 305).
Secret-nailed, by which each board is nailed on the tongue to the joist and covered by the top of the other (grooved) board, which is held down by its (tongued) predecessor (fig. 306).
Dowelled, where small oak or other hard-wood dowels are driven into the edge of the fixed board and the other is cramped up to it, so that the dowel enters both boards and keeps them together (fig. 307). They are secretly nailed obliauely between the dowels.
Fillistertd are similar to fig. 303, " rebated."
Ploughed and tangutd are the same as grooved and tongued (fig. 30a).
A new method of secret fixing has lately been invented. It consists of shouldered brads, one point of which is driven into the joist by hammering the shoulder, and the board is driven down on to it, as in fig. 308-
Headings are the joints of the boards crosswise - ie., where they are not in sufficient lengths to go the length of the room, and have to be in two or more lengths. They may be either square or bevelled, as figs. 309 and 310, or cross-tongued, as fig. 311, or tongued, as fig. 312, or rebated and tongued, as fig. 313.
Floor boards are usually laid in "uniform" thicknesses of from 1 to 1 1/2 inches, and in from 3 1/2 inch to "batten" or 7-inch widths. They should, under any circumstances, have their edges shot - i.e., truly planed, so that they can be "dogged" or "cramped" up tight to each other before being nailed; or they are laid folding in common work, as fig. 314.
In good work the nails should be punched below the general surface of the floor, the boards planed off to one level, and the nail-holes stopped up with putty, before a floor can be said to be complete.
Double floors may sometimes mean that the flooring or floor-boards are laid on the joists in two thicknesses, generally 3/4, or 7/8, and 1 inch thickness, the bottom thickness being straight-jointed, and often laid diagonally across the joists; while the other - either grooved and tongued, or of some other special section - is laid on in the ordinary way above the sub-floor, as the bottom one is called.
The various kinds of floors having been explained to the student, it only remains to say that the principle of wooden beams and girders is antiquated, bad from its elaborate framings, risks to fire, and the sagging and uncertainty of the large-sized members. It has been superseded by iron or steel for binders and girders, the latter being considerably superior in forming a rigid mass, its comparative impunity from fire, etc., but care should always be taken to leave a space between the floor-boards and top of the iron or steel joists for gaspipes, etc.