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How to Install a Bathtub

Bathtub installation

There’s nothing like taking on a home project and completing it yourself. If you choose to replace your bathtub yourself, you’ll admire it every time you take a bath, knowing it was all done with your own two hands. So what do you need to know about installing a bathtub? Here’s what you need to do, step by step.

Choose the Bathtub

The first thing you need to do is actually pick out the bathtub. This might sound simple, but it can be far from it. Most bathrooms are crunched for space, so you’ll want to measure the space carefully, noting the longest and widest dimensions for the bathtub. Ensure that the new tub has the drain located on the same end as the old tub. You’ll also want to consider what hallways and tight corners you’ll have to get the bathtub through to reach your bathroom.

Disconnect Piping

Bathroom Tools

Before you start, examine your work space. If your bathroom is really tight, you might have to remove the toilet and vanity to have enough room to work.

If you’re replacing an existing bathtub, you’ll need to remove the previous tub. Start with turning off the water supply. Next, open a faucet that is below the tub level to drain the water supply lines. Once that’s done, remove the overflow, faucet, and drain. You may need to cut a hole in the wall to access the drain under the tub or you can go underneath the tub into the crawl space, depending on how your house is configured.

Separate Tub From Wall

You’ll have to remove the drywall on all sides of the tub where it meets a wall. About 6 inches should do it. Make a line 6 inches above the tub, making sure it’s even. This will make it easier to replace the drywall when you’re done. Cut along the line with a drywall saw and then remove the drywall between the cut and the tub.

Behind the drywall are nails attaching the bathtub to the studs. Remove the nails using a pry bar. Remove any baseboards on the floor next to the tub that are in the way and cut the caulking that runs along the bottom of the tub and the floor with a utility knife.

Remove the Old Tub

With someone’s help, lift up the tub and slide two one-by-fours, one under the side of the tub at each end. Use this to slide the tub out. If you have a cast iron tub, you can just use a sledgehammer to break it up. To keep debris from flying all around, cover it with a drop cloth and wear protective eyewear and gloves. Other lighter tubs can be carried out of the bathroom to be disposed of. Porcelain over steel should be left whole.

Remove Stringer and Prepare for the New Tub

Unscrew the stringer supports along the edges of the tub where it meets the walls. Clean out any dust or debris.

You’ll want to prepare the area for the new bathtub. Start by making sure that the subfloor is level. If not, you can use a leveling compound to even it out. With it level and clean, you’re ready to install the tub.

Bring in the New Tub


To protect the tub, keep it in the box until it’s in the bathroom. There is likely a dashed line at the top of the box where you should cut the box open. Once you’ve cut it, this outline will rest on the bottom of the tub to protect it during installation.

Inspect the tub to make sure there are no damages or flaws. Once you’ve done this, and assuming the tub’s in good shape, place the side of the box back onto the exposed portions of the tub and tape the box on to protect the tub as you install it. Using the same one-by-fours as earlier, slide the tub into place and mark where it hits the studs on each wall.

Install a New Stringer

Now that you’ve marked where the tub hits the studs, take the tub back out and measure the height of the tub’s edges. Measure that same distance below the marks on the studs and mark this new measurement. Cut a 2×4 the length of the tub and install it across the studs along the second mark using decking screws. This will be the new stringer and will give support to the edge of the tub once it’s installed.

Install the Drain and Overflow

With the stringer in place, it’s time to install the new drain that came with the tub. Refer to the included instructions to install the drain. Using plumber’s putty on the underside of the drain flange, place the drain flange underneath the tub’s drain.

Next is the overflow. You’ll place a rubber gasket onto the overflow elbow and place it behind the overflow site. Using a screwdriver, attach the cover plate on the inside of the tub to the overflow elbow. Then, on the backside of the tub, connect the drain pipe and the overflow elbow with a T-pipe.

Install the New Tub


Using the one-by-fours once again, place the tub into its new home while being careful not to disturb the new drain and overflow pipes. The long edge of the tub will rest on the stringer you just installed. Reconnect the drain underneath the tub to the rough-end drain outlet below your tub. With roofing nails, attach the tub’s flange to the wall by nailing them at an angle. Do this on all sides that meet the wall, including the sides of the tub.

Finish It Off

Now that you’ve installed the tub, it’s time to finish off the project. This includes replacing the missing drywall. Don’t forget to use water-resistant green board drywall rather than normal white drywall. After spackling, texturing, and painting, you can add tile or whatever material you plan to use around the tub. Don’t forget to reinstall the baseboards you removed earlier and caulk where the tub and floor meet.

Now just reinstall the faucet, and your project is complete!

Redoing your tub will give you a feeling of accomplishment and the opportunity to put your own touches on your home.

Bath Tub


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