Copyright Goodheart-Willcox Co., Inc. 324 Section 3 Plumbing System Design and Installation The drain body of the shower base connects to a 2″ drainpipe and is sealed with a rubber compression gas- ket. Some older shower bases are sealed with oakum and lead, Figure 21-17, or oakum and liquid plastic that cures after it is poured around the pipe. This joint is generally made during the second rough stage. During the finish stage, the bathtub drain is con- nected to the DWV piping and the faucets are con- nected to the hot and cold water supply. With the tubs/shower bases in position, it is time to locate the closet flanges for water closet installation in the correct openings. Support the closet flange on blocking equal in thickness to the finished floor mate- rial, Figure 21-18. Check the distance from the wall to the center of the closet flange. Temporarily secure the closet flange with a weight. Assemble the long-radius ell and cleanout at the base of the stack so the ell can connect to the horizontal sewer pipe. The height of the double sanitary tee with side inlet that serves the two water closets is critical to this instal- lation due to the need for 1/4″ of fall per foot of pipe Pro Tip Since both tub and shower bases are installed during the early stages of construction, 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. 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 21-16. 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. 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 bathtubs are se- cured 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 components 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 bath- room walls is completed. It is also very helpful, in re- cessed 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. Installing a shower base is essentially the same as in- stalling a tub. Cultured marble and other types of cast bases are heavy enough to stay in place without fasten- ers. 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.