How to Replace a Shower Drain

To begin work on your shower drain, turn off all circuit breakers that control the lights and outlets in the bathroom you’re working on. Wearing a headlamp for light optimizes safety until you feel confident you know where all the wires are located.

Next, make a rectangular hole in the drywall underneath your shower with a drywall saw and utility knife. Be cautious of any other pipes or wires that may be in the ceiling as well. Continue your cut as far as the ceiling joists on either side. Then, cut down the middle of the joists to provide a backing for the new drywall. Make sure the hole is rectangular as this shape will be easier to patch than any other.

The section should also be large enough to allow you to disassemble your drain. If your shower drain has been leaking, the best place to cut is where the drywall is soggy, or water is dripping. Cut away all the water-damaged and moldy drywall.

This portion of the process is complex and requires several mechanical steps to begin disassembling the portion of the drain inside the shower.

First, wedge a flat-head screwdriver under the drain strainer and pry it up. Next, remove the strainer so the locknut and gasket inside the drain flange are exposed. You’ll see that the locknut has several crowns. Put a screwdriver against one of the crowns and tap the screwdriver with a hammer to turn the nut clockwise. Then, keep tapping until you’re able to turn the nut by hand. Unscrew the crown and remove it. Finish prying out the rubber gasket underneath it with the screwdriver.

Return to the space beneath the shower (either the ceiling or the crawl space) and locate the locknut holding the drain to the shower pan. If space is available, you can use wide-jaw pliers to loosen it. However, if space is limited, then use the same technique described above (i.e., tapping one of its crowns counterclockwise with a screwdriver and hammer until the nut is loose enough to turn by hand).

When the locknut is removed, you should be able to remove the drain housing from the shower pan by lifting it out. If you’re having trouble removing a plastic drain housing, then it’s likely glued to the waste pipe. You can remedy this by cutting the pipe, but do not do this at the connection point. Instead, cut the P-trap assembly at the trap outlet, lift the drain from inside the shower, and remove it from there. While you’ll ultimately need to replace the P-trap, the final assembly will be cleaner.

Before attaching the new drain, wipe the rim of the waste pipe off with a rag. You want to make sure it’s clear of any stray putty or debris before sliding on the locknut, then the fiber gasket, and finally the rubber gasket for the new drain.

To attach these new fixtures, you’ll likely have to pull the pipe away from the drain opening. Once you’ve done this, make sure you return the drain to its original position.

Before installing a new drain flange, wipe away old plumbers’ putty and check the shower floor around the drain opening. If cracks are present, you may need to install a new shower pan before continuing.

If no cracks are present, continue by packing the underside of the rim of the new shower drain flange with plumbers’ putty. Do this by rolling the putty into a rope and winding the rope around the flange. Then, flatten it with your fingers.

You may read about using silicone caulk to seal the flank. This is one way to go about this process, but it could lead to issues later on. Silicone is an adhesive, and thus, you may have difficulty removing the drain in the future if you need to replace it again.

Drop the flange into the drain opening and fit the flange around the end of the waste pipe.

Head back to the area underneath your shower — whether this is a ceiling or crawl space. Slip the two gaskets over the threads of the drain flange and screw on the locknut. Make the locknut as tight as possible, working at first with your hands and then with wide-jaw pliers or a hammer and screwdriver.

If you cut out the old drain and P-trap, reassemble these pieces now. Be sure to pack the drain flange with plumbers’ putty and then feed it through the hole. Finish this process by sliding on the fiber and rubber washers and then screwing on the underside of the drain fitting.

After the drain is assembled, glue the P-trap assembly to the shower drain and drain line.

Make sure you check your work, so you don’t end up replacing your shower drain sooner than you need to. To do this, snap the strainer onto the drain flange and turn on the shower faucet. Allow the water to run for a few minutes. Go downstairs and watch for any signs of dripping water in your ceiling — using a flashlight to check for staining.

If you do see water dripping or beading, tighten both locknuts until the water seepage ceases entirely.

The final step of replacing a shower drain is cutting a piece of drywall that fits in the rectangular hole you made. Screw this drywall into the ceiling joists with drywall screws and then tape and finish the joints with drywall tape and drywall joint compound.

To make a smooth repair, you’ll likely need to use a minimum of three coats of joint compound. After it dries, prime and paint the patch. For a more seamless look, repaint the entire ceiling.