The floors in the better sort of town houses and palazzi, are formed of joists of fir timber, very commonly round as it grew, from 6 to 9 inches in diameter, placed at about 3 feet apart. The ends are inserted some inches into the walls, but are neither bedded on, nor connected by, any "tossils" or bond timbers, none of which are ever placed in the walls. Upon these joists a planking of fir, oak, or chestnut, from an inch to an inch and a half thick, is laid, rough as it comes from the saw, and pegged or spiked to the beams, and upon it a bed of concrete or beton, composed of lime, mortar, and broken tufa, brick, or stone is laid, to 6 to 8 inches in depth, and the surface of the latter is laid with red tiles—square or hexagonal—or sometimes plastered over with puzzolano mortar, and painted in oil.
The under surface of the floor is often bare, and the joists visible; in other cases a plastered ceiling is secured, by heavy lathing, up to the joists. See Photog. No. 12 at St. Pietro (Coll. Roy. Soc.)
A floor of this sort weighs from 60 to 100 lbs. to the superficial foot. Floors of palazzi, are also not unusually formed of arches and groins, built of hollow pottery embedded in mortar, the haunches filled in with beton, and plastered soffeits, with tiled surfaces to the floors, which, thus constructed, are of still greater weight.
The roofing also usually consists of round fir timber. The framing is of the simplest character except in some church and other roofs of great span, when the timber is squared. It consists commonly of principal rafters at 3 to 5 feet apart, connected by a rude collar brace, of round fir also, trenailed or bolted to the rafters. The feet of the rafters sometimes rest upon a wall plate of squared
