How to Replace a Shower Valve

To find the right replacement valve, you’ll need to know the brand and type of faucet and familiarize yourself with the parts of a shower valve. If you can’t find any markings, you’ll need to take apart your faucet and take measurements or bring it into your local supply store and ask for help. Additionally, be sure to purchase the same brand and the correct fittings or adaptors, depending on the type of piping in your bathroom. 

“You’re going to do way better at the local supply house, not the hardware store,” says Joseph Wood, Expert Review Board member, Master Plumber, and Founder of Boston Standard Company. “And you should go to one that sells the same brand of fixture you're trying to get.”

Changing the shower valve cartridge (the internal mechanism) will solve the problem most of the time, but you might need to change the entire shower valve assembly. Call a plumber near you to take on the job if you’re upgrading to a different system.

Cover the shower or bathtub drain with a cloth or a drain stopper. You don’t want to lose any important screws or parts down there, not to mention risk clogging your drain.

Use the screwdriver (or the Allen wrench, depending on the screw on your shower valve) to unscrew the shower handle. Sometimes the screw is underneath the decorative shower handle cap. Keep your handle, screws, and any caps to the handle together so you can easily find them when it’s time to put the shower back together.

Take off the trim plate covering the hole in your shower wall (the shower-side wall, to be exact). If there’s caulking between the plate and the shower wall, cut through it with the utility knife. Now you should be able to see your valve.

Here’s your chance to give the shower handle and trim plate a good cleaning. Soak them in vinegar until it’s time to put them back on.

Shut off the water to your shower. There should be a shut-off for the hot and cold water on each side of the valve. If you can’t locate them, go ahead and shut off the main water valve in your home until you’ve finished this project. If you use a well, turn off the well pump circuit breaker.

If the existing hole behind your trim plate is smaller than 12-by-12 inches, you may need to cut a larger hole with the hacksaw to access the valve. First, measure your trim plate using the tape measure. Make sure the new hole you create isn’t bigger than the trim plate. Otherwise, it won’t cover the hole when you put it back together.

If your existing shower valve has a cap, remove it by taking out the screws on either side. If there’s a valve clip at the top of the valve, remove it using the needle-nose pliers and set it aside. Check to see if your existing valve also has a retaining nut that holds the valve in place; if it does, hold the valve while you unscrew the nut with the wrench and keep it with your valve clip.

If changing the shower valve cartridge alone isn’t going to cut it, you have to replace the entire shower valve assembly. You’ll have to access the valve from the other side of the shower wall. Using the drywall saw, cut out a section of drywall (about one foot by one foot). The valve will be attached to a stringer (a supporting board between the studs) that you’ll have to cut loose with a reciprocating saw.

Disconnect the shower valve from the pipes running to the shower and the hot and cold lines. If you have copper pipes, cut the pipes with a tubing cutter.

Connect the piping to the new shower valve using the correct fittings, connectors, or adaptors. You may have to cut new piping to attach to the valve. Follow the instructions that came with your replacement shower valve for guidance. 

If you have PEX piping, wrap the male threads with plumber’s tape before attaching them to the female fittings. Next, attach couplings and pipe-crimp fittings. If you have copper pipes, you can solder the piping or use compression fittings.

The instructions will also specify where to position the valve so it’s the correct distance from the shower wall and the drywall. Depending on the shower valve you purchased, you may have to install the shower valve cartridge as well.

If you replaced the entire valve assembly, reattach the stringer between the studs in the wall to provide support.

Replace the cap, valve clip, and retaining nut as needed to secure the valve back into position.

Turn the water back on at the hot and cold shut-off on each side of the valve or at the main water valve for the home. Check all connections for possible leaks before turning the water back off.

If you replaced the entire valve assembly, you’ll need to repair the drywall covering the assembly and the stringer. 

Create a patch with a piece of drywall the size of the hole. Attach furring strips with screws, and screw the patch into the strips. Apply joint tape around the edges of the patch and cover the entire patch with joint compound. Once it dries, sand and paint the area.

Replace the trim plate and the shower handle. If necessary, apply more caulking around the trim plate to make it watertight and look good as new.

Turn the water back on and enjoy your functional shower.