How to Install a Shower/Bathtub

Here we offer general instructions and precautions for roughing in, as well as installation procedures for tying into your present drain waste vent and supply systems. When all the roughing in has been completed and you are ready to assemble your shower and bathtub, your rough plumbing should resemble that shown here.

Most Common Mistakes

1. Violating or ignoring local code restrictions,
2. Using pipes that are too small,
3. Attaching copper to galvanized without using a brass or dielectric fitting between the two,
4. Not using PTFE tape or pipe compound at threaded joints,
5. Not leveling your fixtures when installing them,
6. Not installing an air gap filling for fixtures,
7. Cutting supply stub outs too short to install the shutoff valves onto after the finished wall is in place, or
8. Not properly aligning tubing into fittings or stop valves. (Forcing the nut onto the compression ring at an angle when the tubing is at an angle will cause a leak.)
9. When turning the water back on in your home, always run the outside hose valve or flush your toilets to bleed dirt and air from the lines. This debris can cause problems in your sink faucets and other plumbing trim.

Installing Your Shower and Bathtub

Pipes required include the hot and cold supply lines and a pipe leading to a shower head. A mixing valve and shower head are also needed. Air chambers may be required.

Bath/shower fixtures also rate low in fixture units and are often positioned on branch drains and wet or back vented as are the sinks. Both shower stalls and tubs enter the stack at floor level or below because of the position of the floor drain trap. The faucet and shower head assembly require an open wall for installation. Remember bathtubs and shower stalls may require support framing. A bathtub filled with water is extremely heavy, so check building codes and framing support before installing the tub. The minimum floor area required for a shower stall is 1,024 square inches, and you should allow 24 inches from the stall itself to any other fixture or wall.

1. Install all piping before installing the tub itself.
2. Lower the tub into place so that the continuous flange fits against the wall studs and rests on 1 x 4 or 2 x 4 supports. Anchor the tub to the enclosure with nails or screws inserted through the flanges into the studs.
3. Assemble the drain connections by connecting the tub overflow with the tub drain ABOVE the trap, not beyond it. The trap will have a compression fitting that screws over the arm of the overflow assembly.
4. Hot and cold water lines are run to the tub/shower mixing valve where they are attached, usually by, sweating these directly into the hot and cold ports of the mixing valve.
5. Run a pipe up the wall for the shower head. On the top of this pipe, sweat on a brass female threaded winged fitting that is nailed or screwed into a framing support.
6. Extend a piece of 1/2" pipe, according to the manufacturer's instructions, for the tub spout. Sweat on a male threaded fitting at the end of the pipe or use a brass nipple of the proper length and a 1/2" cap.
7. At this time you will need to have your rough plumbing inspected.
8. Restore water pressure and check the drain connection and the supply pipes for any leaks.
9. Replace the wall with moisture resistant drywall as a base for your wall covering. Seal joints between the wall and your new tub with silicone caulk as protection against water seepage.
10. Install the Spout, handles and shower head. The shower head screws onto the shower arm stub out. Whether installing a new shower head or replacing an old one, always clean the pipe threads and apply new pipe joint compound, PTFE tape or both to prevent leaks.