Installing a shower base is essentially the same as installing a tub. Cultured marble and other types of cast bases are heavy enough to stay in place without fasteners. Molded plastic bases have a lip that extends under the wall materials and is held in place by screws. The fasteners must be driven and spaced according to the manufacturer’s directions. The drain body of the shower base connects to a 2″ drainpipe and is sealed with a rubber compression gasket. Some older shower bases are sealed with oakum and lead, Figure 19-17, or oakum and liquid plastic that cures after it is poured around the pipe. This joint is generally made during the 2nd rough stage. During the finish stage, the bathtub drain is connected to the DWV piping and the faucets are connected to the hot and cold water supply. Since both tub and shower bases are installed during the early stages of construc- tion, they must be protected from damage while the interior of the building is being finished. The shipping carton can be cut to cover the tub or shower base. The recessed installation, Figure 19-16, is common. Rough-in dimensions for the length and width of the tub are known before interior walls are constructed. After the walls are framed and blocking is installed, the tub is set. Plastic and enameled steel tubs are secured with screws driven into the studs or blocking at locations specified by the manufacturer. Be careful not to overdrive screws because they may crack plastic or the enamel coating on a steel tub. Cast iron tubs are heavy enough that they are not fastened to the frame. The wall covering—drywall, plaster, or tile—is attached to the studs by other trades after the bathtub is in place. It may be desirable to install the drain compo- nents that attach directly to the tub or shower base before the unit is put into its final position. This can eliminate the need to work in a confined space while assembling these components. One-piece molded plastic tub/shower units are too large to pass through most door openings. Therefore, they must be installed before the framing for the bathroom walls is completed. It is also very helpful, in recessed installations, if one wall of the recess is not framed until after the unit is positioned. This allows for easier alignment and installation of the unit. Hot water supply pipe Cold water supply pipe Opening for DWV piping 1 × 4 to support tub rim is securely fastened to studs Access panel will be installed on outside wall to permit servicing the bathtub faucet and drain A B Goodheart-Willcox Publisher Figure 19-16. Bathtub installation. A—In a recessed installation, walls enclose the tub on three sides. B—A ribbon of 1 × 4s is attached to studs to support the tub rim. Chapter 19 DWV Pipe and Fitting Installation 309 Copyright Goodheart-Willcox Co., Inc.