Install a fiberglass shower stall over a concrete floor using a special drain assembly that eliminates leaks. You run the drain line under the concrete.
A shower usually requires a 2-in. drain, with the P-trap located under the concrete slab.
If you want to install a shower over a concrete floor, a fiberglass shower stall will work just fine. Ideally, you’ll already have a drain roughed in, with the pipe sticking a few inches above the floor. Otherwise you have to break through the concrete to run a new line.
If you have a pipe stubbed up, call the plumber or contractor who did the work to confirm it. The 2-in. pipe is typically the shower or tub drain. Line it up exactly with the drain hole in the bottom of your shower bay. This position determines the location of the stud walls around the shower. The supplier may be able to provide a dimensioned drawing of the shower bay, so you don’t actually have to put it in first.
If the existing 2-in. drainpipe isn’t where you want it, you’ll have to break up the concrete and replumb the drain.
Make sure the drainpipe extends at least an inch above the concrete. If the pipe is too short, you’ll have to break up the concrete and extend it. Also, you’ll need at least a 1-1/2-in. space between the pipe and the concrete to accommodate the drain assembly (see photo below). If there isn’t, carefully chisel out the concrete around the pipe.
Tip: If you’re considering a single-piece shower bay, make sure you can get it into the new bathroom space. You may have to bring the unit into the space before framing the doorway or walls. If access is a problem, check out multiple-piece units that will fit through doorways more easily.
The assembly locks tightly to the pipe and clamps to the edge of the shower base to make leakproof seals.
After you frame the shower walls to fit the shower bay, lay the bay on its back and install the drain. Use a special leakproof drain assembly called the No-Caulk Shower Drain. It’s available at home centers and plumbing supply houses. Although these drain baskets are available in plastic, I’d opt for the brass one. Follow these steps to attach the shower to the drain:
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.