Terrace Roofs.
Terrace roofs have been much used in and about London. They are formed of thin arches of tiles and cement, supported on cast-iron bearers or ribs, which are placed about three feet apart. The arch is composed of three courses of common plain tiles, bedded in fine cement without sand. In laying the tiles, laths or small slips of wood are used, resting on temporary bearers between the iron ribs; the laths being shifted as the work advances, in the course of about half an hour after the tiles are laid. Particular attention is required in bonding the tiles both ways; and they are rubbed down closely upon each other, much in the same manner as a joiner glues a joint. Sometimes these terrace roofs are coated with a layer of coarse gravel, and then with nine inches of good soil, so as to form a terrace garden. The roofs of two taverns at Hungerford Market are formed of these cemented tiles.