CARCASE, or NAKED FLOORING, that which supports the boarding above, for walking upon, and the ceiling below, by a grated frame of timber, consisting of three tiers of beams, called joists ; the middle tier being transverse to the other two. The beams of the middle tier, called binding joists, support the other two tiers : the beams forming the upper tier, called bridgings, or bridging joists, support the boarding, and are frequently notched upon the binding-joists : the lowest row of beans, called are either framed into the bindin,7-joists, with pulley or chase mortises, flush with the under edges of the said joists, or are notched and nailed to them below. When the floor is very much extended in both dimensions, another set of large beams, called girders, the whole depth of the three tiers, are introduced, for short ening the bearings of the binding-joists, which are mortised and tenoned into the girder on both sides of it. The under edges of the binding-joists should be so framed, as to be below the under side of the intermediate girder, about half an inch, to prevent the ceiling from cracking ; and the girder must be furred, to range with the under edge of the ceiling joists. The general scantlings of these timbers are as follow, viz., girders, 12 by 13 inches ; binding-joists, 10 by 4 ; bridging joists, 5 by 21 ; and ceiling-joists, 3 by 21. The distance
which these timbers are commonly placed in the clear is as follows : the binding,-joists from 4 to 6 feet, which is also that of the ceiling joists; and the bridgings 11 or 12 inches apart. As the girders go the whole length of the room, they have no fixed bearing ; when they extend to 20 feet and upwards, they should be trussed. When the breadth of a room extends to 30 feet and upwards, the girders should be framed like the truss of a partition, with an upper and lower beam, and with posts, braces, and struts : for this purpose, a sufficient depth for the floor should be allowed, from two to three feet. Girders should never be placed over openings, unless they be supported by strong arches. When a lintelled opening comes under the place where the end of the girder should he, the end of the girder must be changed to the nearest solid bearing, which will throw its direction into an oblique position. The wall-hold for girders in brick buildings, may be from 9 to 12 inches, and for binding-joists, 6 inches. In stone buildings, for girders, from one foot to two feet, according to the thickness of the wall, and for binding-joists, 9 inches. In thick walls there may be two rows of wall-plates.