One full day of labor, plus additional time to repair walls.
Cost
$500–$1,000
You’ll spend a lot on supplies, but you may still save money by DIYing.
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What you'll need:
TOOLS
Safety glasses
Ear protection
Work gloves
Measuring tape
Pencil
Bubble level
Tub drain tool
Adjustable pliers
Screwdrivers
Hammer
Utility knife
Caulk gun
Drill with screwdriver bit
Prybar (optional)
Sledgehammer (optional)
Reciprocating saw (optional)
Mortar mixing tools (optional)
Allen wrench (optional)
Strap wrench (optional)
SUPPLIES
Tub-and-tile bathroom caulk
Exterior grade screws
Plumber’s putty
Two-by-four-by-five lumber
Cardboard
New bathtub
Exterior grade flat washers (optional)
Roofing nails (optional)
Mortar (optional)
Shims (optional)
Replacing your bathtub is a big project that can beautify your bathroom and make bath time inviting again. You can employ your intermediate DIY skills with patience and a helper to accomplish the job over a weekend. If you’re up to the challenge of learning how to install a bathtub, removing and replacing your tub can save you money over a complete bathroom remodel, and you’ll save big by providing the labor yourself.
Prepping to Replace Your Bathtub
The key to success when installing a new bathtub is to make sure the new one fits perfectly in the void left by removing the old tub. Most alcove-style bathtubs measure 5 feet long and between 28 and 34 inches deep. It’s challenging to get an exact measurement from the existing tub while it’s still in place. Fortunately, bathtubs come in standard sizes, so your educated guess from the tape measure will be the correct measurement.
Choose a new bathtub with the drain location on the same side as the existing drain. Before starting work on the bathtub, remove the tub spout if it's less than several inches from the top of the tub. Use an Allen wrench or strap wrench to remove it, depending on the style of the spout.
You won’t have to work directly on the water supply lines unless you plan to install new fixtures for your tub. However, it’s good practice to turn off the water supply for this project to avoid cleaning up a lot of water after bumping a live tub handle.
Locate and remove the access panel on the other side of the wall on the plumbing end of the bathtub. If no access panel is present, check the basement ceiling for access to the plumbing from below.
If the basement option doesn’t work, you can turn off the house’s water main valve or cut open a small section of drywall where the access panel should be. Now is an excellent time to create an access panel if one doesn’t exist.
When you gain access to the plumbing, turn off the hot and cold water control valves. However, if there aren’t any control valves, turn off the house’s water main valve.
The first step of removing a bathtub is disconnecting its plumbing. Use a tub drain tool to twist the drain counterclockwise and remove the top section. Use a screwdriver to remove the faceplate of the bathtub overflow drain.
Use a pair of adjustable pliers to disconnect the tub’s plumbing below the tee where the main tub drain meets the overflow drain. Remove the plumbing sections. If you’re in an old home and suspect the presence of lead drain pipes, contact a local plumber to handle the situation.
This step isn’t always necessary, but if you’re installing a new bathtub faucet or it’s low enough that it will be in the way during removal and installation, you can go ahead and remove the faucet. To remove the bathtub faucet handles, remove the handle covers with a flathead screwdriver and then unscrew the screws that hold the handles in place. Gently pull them from the wall and off of the pipe. If the handles are difficult to remove, you may need a handle puller for this step.
To remove the bathtub spout, first check for a setscrew on the underside of the spout. If there’s a setscrew, you have a slip-on spout and will need to loosen the setscrew before pulling it off. If there isn’t a screw, you have a screw-on spout.
To remove a screw-on spout, you’ll need a pipe wrench or other tool that can help you loosen it. If you’re going to replace the original spout, put a towel around the spout to protect it from the wrench.
Access the Tub Flange
A bathtub is more than it appears on its surface. Under the tub surround, tile, or other wall finish is a flange that acts as flashing to keep water away from the walls. You’ll need to expose the flange to remove the bathtub.
Mark a level cutting line several inches above the top of the bathtub. Tile grout lines make an excellent cut location. Remove the grout and tile below the line or cut away the tub surround or other wall finish material.
Score and remove the cement board, drywall, or plaster underneath the wall finish below the cut line, and continue removing material until you reach the wall studs.
Remove the Bathtub
Now, the process of bathtub removal starts. Place a piece of cardboard or thin plywood in front of the tub to protect the floor from damage. Use a pry bar, screwdriver, or a drill and screwdriver bit to remove the nails or screws that secure the tub flange to the wall studs. Slide the tub several inches from the wall and onto the floor protection.
While wearing safety glasses and work gloves, cut the tub into several pieces with a reciprocating saw and an appropriate blade for fiberglass, composite, or steel bathtubs. For cast iron tubs, carefully break the tub into pieces with a sledgehammer. Use caution not to damage the floor or walls, and work slowly. If necessary, remove the pieces of the bathtub and dispose of them properly with a helper.
If a stringer board or tub-edge support board is present, remove it with a pry bar or a screwdriver bit on your drill. Chip away the old mortar bed if one exists.
Dry fitting means setting the new tub in place without mortar or adhesives to ensure it fits into place. Once the tub is in place, check the location of the drain and the bathtub’s alignment; make sure everything is lined up and level. During this step, you can mark the location of the supports for the next step.
Install Supports
A stringer board supports the long edge of the bathtub where it meets the wall. Slide the new bathtub into position with the aid of your assistant. Use a bubble level to check that the tub rests level in all directions. If the tub doesn’t sit level, remove the tub and level the subfloor under it with a leveling compound or another method.
Mark the top of the flange on each wall stud across the long side of the tub. Remove the bathtub from its position, and measure the distance from the top of the flange to the underside of the tub’s lip. Transfer the measurement to the marks on the studs. The new marks represent the top edge location of a new stringer board.
Cut a two-by-four board to match the length of the bathtub. Line up the two-by-four’s top edge with the lower marks on the stud and attach it with exterior grade screws to each stud.
Install the Drain Parts
Use the tub drain tool, adjustable wrench, and plumber’s putty to install the main tub drain parts. Using a screwdriver, install the overflow faceplate and pipe. Attach the two drain pipes with a drain tee, but don’t install the P trap tube yet—one of the many helpful plumbing terms to know if you don’t already.
Create a Mortar Bed
Many modern bathtub models include an insulating support structure on the bottom. If yours has its own support, you can skip this step.
Mix a bag or two of mortar with water until it reaches the consistency of peanut butter. Spread a 2-inch thick layer of mortar where the tub will rest. Stay several inches clear of the primary drain location.
Set the bathtub in place with your helper and gently step into the tub. Use your body’s weight to set the tub into the mortar bed. Double-check that the tub is level.
It’s time for things to start looking like a bathroom again. You’ll need to secure the new tub to the wall. Use roofing nails or exterior grade screws and flat washers for this step. Check that the tub flange rests flush with each wall stud. Place shims behind the tub flange on any studs that aren’t flush.
Install a screw with a washer or roofing nail at each stud. Place the fastener above the flange so the washer or nailhead overlaps the edge. Use caution not to damage or bend the flange.
Connect the Plumbing
Finally, it’s time to reconnect the plumbing. Connect the tub drain tee to the P trap and the house’s drain plumbing. Tighten each pipe fitting one-quarter turn with the adjustable pliers, and reinstall the tub spout.
After, during, or before this last step, turn the water back on when appropriate. Caulk the front edges of the bathtub, and repair or refinish the bathroom wall. Allow the caulk and new finish to cure for a day before using your new tub.
DIY Tub Installation vs. Hiring a Pro
Removing and replacing a bathtub is an intermediate to advanced DIY task that can save you an average of $2,000 in labor costs from the total cost of tub replacement. However, precise installation methods are necessary for success. Unfortunately, less-than-perfect installation can cause expensive water damage.
If DIY tub installation doesn’t sound like your favorite way to spend a weekend, a nearby bathtub installer can perform the job for between $1,400 and $7,000. If you’re considering replacing your bathtub with something bigger or doing some remodeling, planning for overall bathroom remodel costs may be the way to go.
You can resurface or reglaze your bathtub, and it’s faster and less expensive than replacing a bathtub. Plus, replacing a bathtub is an extensive and intrusive process that requires wall repairs. Refinishing is an excellent option if the old one is in good working condition.
There are also options to install a bathtub liner over your existing tub. However, if you’re seeking a new bathtub with new features, you’ll likely want to replace your tub.
You can put a structure under your bathtub for support. Many modern tubs come with a built-in support structure underneath. Almost any type of mortar or floor-leveling compound is acceptable for new bathtubs that don’t include a support structure.
You can also install spray foam under an existing bathtub to eliminate or reduce squeaking or sagging. However, spray foam isn’t rigid enough for primary tub support.
There is no reason to install flooring underneath a bathtub. A bathtub with proper installation will keep water from reaching the unprotected subfloor underneath. Also, a small leak from a tub drain may be more difficult to notice if finished flooring impedes water drips.
Deane has spent 30+ years in residential construction, contracting, remodeling, maintenance, and home repair, and now contributes DIY and educational articles for publications like Forbes Home and U.S. News. Throughout his career, he has strived to help homeowners find the potential hidden within the walls of every home and empower them to take control of their household repair and remodeling endeavors.
Deane has spent 30+ years in residential construction, contracting, remodeling, maintenance, and home repair, and now contributes DIY and educational articles for publications like Forbes Home and U.S. News. Throughout his career, he has strived to help homeowners find the potential hidden within the walls of every home and empower them to take control of their household repair and remodeling endeavors.
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