How to Replace a Bathtub With a Shower

Plan the Shower Footprint

Where feasible, choose a shower stall and pan that has the same footprint size as the bathtub. Many tubs are 60 inches long, with widths that vary from 30 to 36 inches, or sometimes even wider. It's generally fairly easy to find shower pans and surround kits to match standard bathtub sizes. Keeping the same footprint will avoid excessive repair work on the walls and the flooring since the shower pan and surround panels will cover the old footprint.

If you decide to change the size of the footprint—for example, installing a square 32 x 32-inch shower in the space vacated by a 30 x 60-inch tub—you should plan on a considerable amount of extra work modifying the flooring and finishing the walls.

Shut Off the Water Supply

Before beginning work, shut off the water to the bathtub. The hot and cold water supply pipes leading to the bathroom may be equipped with branch shut-off valves, or there may be fixture shutoff valves at the point where the supply lines connect to the tub faucet. If there are no visible shutoff valves of either kind, then you will need to shut off your home's main water shut-off valve before continuing.

Remove the Wall Surfaces

Use the appropriate demolition tools to remove the wall surfaces around the tub, as needed. In some cases, it may involve simply tearing out an existing acrylic or fiberglass tub surround, a job that's done easily with an oscillating multi-tool and pry bar. For a wall covered with ceramic tile, a hammer and pry bar are the main tools needed. Make sure to wear eye protection and hearing protection during demolition.

The amount of demolition needed will depend on the shower kit you have selected. You will almost always need to remove the entire surface of the"wet wall" that contains the faucet and plumbing pipes, and it's often necessary to also remove the other wall surfaces where the shower stall will fit—at least up to the height of the new shower stall, which typically is at least 72 inches (6 feet) tall. Bathtub removal is often simpler if the wall surfaces of all three alcove walls are removed.

Disconnect the Plumbing

Next, disconnect that bathtub's drain, then disconnect and remove the bathtub faucet where it is mounted inside the wall. If the faucet has been fitted with fixture shutoff valves, remove the plumbing back to where the branch lines connect to these shutoff valves. It's generally best to install all-new plumbing for the shower, rather than to try and adapt the old faucet valve with an extension pipe to add the showerhead.

Remove the Bathtub

Removing the bathtub can be a relatively easy task if the tub is made of acrylic or fiberglass, or it can be quite difficult if you are removing a very heavy cast-iron tub.

Begin by removing any screws, nails, or brackets that hold the bathtub's edge flange to the walls. If the tub is heavy, employ the aid of a helper to tip the tub onto one side to remove it. With cast-iron tubs, it's best to tilt the tub up on end, then use a moving dolly to roll it out of the bathroom.

With an acrylic or fiberglass tub, you can often use a reciprocating saw to cut the tub into manageable pieces for removal. You may find that your bathtub was bedded in a layer of mortar laid over the floor when it was installed. If so, removal may require some prying with a crowbar to break it free of the mortar for removal.

Thoroughly clean the demolition area, removing nails and screws from studs, and any debris or mortar from the floor.

Inspect and Repair the Subfloor and Studs

With the bathtub removed, inspect the condition of the exposed wall studs and the subfloor where the tub was installed. Light carpentry work may be required to fix some of the studs or the subfloor where it is exposed by the removed tub.

If the subfloor beneath the tub experienced any water damage, it is best to cut it away and install new 3/4-inch plywood subflooring over the tub area where the shower pan will be installed.

Make sure to cut the necessary opening in the subfloor for the shower pan's drain opening. The shower drain opening for the new shower pan will probably be located in the center of the pan, while the drain openings for bathtubs are usually at the end. So it's likely you will need to do some carpentry and plumbing work to move the location of the drain before installing the shower pan. Some DIYers choose to hire a plumber to do this piece of technical work.

Rough-in the Faucet and Showerhead

In addition to altering the drain lines as needed, the plumbing rough-in stage involves mounting the shower valve and showerhead arm on the studs, as well running the necessary pipes from the hot and cold branch lines, and between the shower faucet valve and the showerhead. Though the work is not necessarily difficult, a good amount of knowledge and experience with plumbing is required to do this work.

The shower valve will be positioned considerably higher than the old bathtub faucet valve—typically at 45 to 48 inches above the shower floor. The standard height for the showerhead is 78 inches. Both the faucet and the showerhead should be centered within the planned width footprint for the shower pan—for example, at 18 inches from the back wall if the shower will be 36 inches wide. The surround kit may give you some instructions on the proper position for both the shower faucet valve and the showerhead.

There are a number of ways to connect the faucet and showerhead to the existing water supply pipes. If your existing plumbing system is made with copper pipe, you can join it to the shower valve with similar copper piping. But many people choose to use PEX pipe for any new water supply pipes, connecting them to existing copper with convenient push-fit fittings. Most people find PEX easier to work with than copper pipes and fittings.

Rough-in the Shower Drain

Before installing the shower pan, the drain pipes will need to be roughed into the position and height required by the shower pan. Measure the dimensions of the shower pan and its drain opening, then extend the drain lines as needed. In most homes, the existing drain lines are made of PVC or ABS plastic, and moving drain lines is a fairly easy matter of cutting off existing pipes, then attaching new pipes and fittings, including a drain trap, to the position of the new shower pan's drain.

General practice is to leave the drain riser pipe slightly long, so it will extend up through the drain opening of the shower pan. The riser will be cut down to size when you test-fit the pan.

Working with PVC pipe is relatively easy, though it can be slightly more complicated if you are transitioning the new PVC to a different type of drainpipe, such as steel or iron pipe. Any homeowner who has some experience with cutting and gluing plastic plumbing pipe—or who is willing to learn the skills—can readily do this work.

But this is the time when you may want to consider hiring a plumber to make a more sweeping system upgrade, perhaps by replacing an older metal pipe system with PVC plastic.

Install the Shower Pan

Follow the manufacturer's directions to install the shower pan. First, test-fit the shower pan and note the position of the drain pipe riser extending up through the drain opening. Mark the drainpipe riser at the correct height, then remove the drain pan and trim down the drain pipe. Be very precise about this, carefully following the shower pan's instructions for the height of the drainpipe.

Most pans are made of acrylic or fiberglass, and in many cases, the directions will call for troweling on a bed of wet mortar to create a solid base that does not flex. Position the shower pan in the mortar bed, with the drainpipe riser centered in the drain opening, then attach the lip of the shower pan to the wall studs with nails or screws. Take pains to make sure the lip of the shower pan is level in both directions, which will ensure proper water drainage in the bottom of the pan.

If the pan has been positioned in a bed of mortar, let the mortar dry at least overnight before continuing work.

Install the Shower Surround Panels

Install the shower's surround panels, as directed by the kit instructions. In most cases, the large back panel is installed first, followed by the solid end wall. The faucet/showerhead panel is installed last. This final panel will need to be drilled out to provide openings for the faucet valve and the showerhead arm. It's critical that this final panel is correctly aligned with the faucet valve and the stub-out for the showerhead, so make sure to be precise when drilling the holes.

The surround panels are usually nailed to the studs, but they may also require construction adhesive to secure them. Installation methods may vary somewhat, depending on the design of the shower surround kit.

Connect the Shower Drain

Attach the shower pan's drain fitting to the drain pipe, as directed by the manufacturer. Use considerable care here to ensure a watertight fitting. Installation methods may differ somewhat, depending on the type of drain fitting you're using, but it generally involves placing a sealing washer or gasket around the tailpiece of the drain assembly, then inserting the drain fitting into the drain pipe. A bead of caulk or rubber washer under the drain fitting's flange provides a seal between the drain fitting and the shower pan as it is screwed down.

Attach the Faucet Handle and Showerhead

Complete the installation of the shower faucet and showerhead, following the manufacturer's instructions. Normally, the faucet body and showerhead arm will already be installed, so completing the installation is a matter of attaching the showerhead, the faucet handle, and escutcheon plates.

Apply a bead of silicone caulk around the escutcheon plates to prevent water from seeping into the wall.

In some communities, a second plumbing inspection is required when fixture connections are completed. If so, now is the time to arrange for the final inspection.

Install the Shower Door

Install the shower door, according to directions supplied by the manufacturer. Methods will vary, depending on whether the door is a sliding model or a swing-out door. Generally, it will involve attaching metal tracks to the shower pan and end walls, hanging the door, then caulking around the track.

Test the Shower

Make sure all joints are sealed with caulk, then turn on the water and test the shower. Look carefully for leaks at all the vulnerable points: around the drain opening, at water supply connections, around the shower door, and around the surround panel seams. The kit instructions will give you details on where you should caulk.