In this tutorial, you’re going to learn how to replace the bathtub in your bathroom step by step.
You’ll learn how to remove your old alcove bathtub, how to choose a new bathtub, and how to hook up the plumbing and install your new bathtub WITHOUT having to access the plumbing from underneath.
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Materials Required:
- Bathtub (I used the Delta Classic 400 Tub in White)
- Bathtub Drain Assembly
- ABS Glue
- Additional ABS plumbing fittings to attach to house plumbing
- Floor Leveling Compound
- DAP Kitchen, Bath, and Plumbing Silicone Sealant
- 1 5/8″ Pan Head screws
- Shims
Tools Required
- Tub Drain Remover
- Level
- 12″ Finishing Trowel
- Cordless Drill
- Caulking Gun
- Saw (Hacksaw, miter saw, or circular saw)
- Reciprocating Saw
- Drill Bits
Step #1 – Removing Your Existing Bathtub
To remove your existing bathtub, you’ll first want to remove the tub surround or the tile around the bathtub. Without doing this, you won’t be able to pull the old tub out or install the new tub.
Once the entire tub is exposed, you’ll probably find some nails or screws securing the tub to the wall. Remove those.
Now it’s time to disconnect the plumbing. Start by removing the drain stop by simply unscrewing it. Then, take a tub drain remover, insert it into the drain, and twist it out counter-clockwise. You may need to insert a screwdriver for more leverage. Then, take a screwdriver and remove the cover plate from the overflow drain.
You’re not quite ready to remove the tub yet, however. First, you’ll need to remove the 2×4 stud on the side of the tub opposite of the drain that the side tub flange was attached to (see the video for more detail). Then, you can lift out the tub by lifting the side opposite of the drain and then pulling the tub out at an angle.
Step #2 – Prep For the New Tub
Bathtubs need to be installed so they have solid, consistent support, and they need to be level.
If you’re installing a new acrylic or fiberglass tub, it probably has a plastic base used to support the base of the tub. If so, then you’ll need to make sure your floor is flat and level – otherwise, your tub will drain improperly, or it could creak and crack when you step in it. Use a floor leveling compound such as the one listed above in the materials list to level the floor.
If you’re installing a cast iron tub, then you don’t have to worry about leveling the floor because you’ll be pouring a bed of mortar to set the tub in. However, you will want to screw some 2×4’s to the wall to support the tub’s rim if you’re using a bed of mortar.
Also, make sure the drain cutout on the floor is the appropriate size for your tub according to the specifications that came with your new tub.
Step #3 – Assemble the Bathtub Drain Assembly
This is the fun part, especially if you liked building legos or models when you were a kid.
Lay the bathtub on its side so you can easily access the drain holes from underneath and from the top.
Then, take a drain assembly (sold in kits) and start by attaching the drain and the overflow drain to the bathtub. When connecting the drain, the rubber gasket goes between the drain elbow and the bathtub – not on top of the bathtub.
Now that the drains are connected to the tub, cut the ABS pipes to the correct length and glue the drain assembly together using ABS glue. Make sure the connections are in the right direction so the water can drain properly.
Now, remove the finished drain assembly from the bathtub.
Step #4 – Connect the Drain Assembly To the House Plumbing
The key here is to get the drain assembly to line up where the bathtub will be before permanently installing the bathtub. To do that, you’ll need to set the tub in place, mark where the drain is on the floor or on a temporary piece of wood, and measure the distance between the floor and the bottom of the drain. Basically, you need to know the exact location of the drain after the final installation.
I demonstrate how to do this in the video at the top of this page. It needs to line up perfectly. Otherwise, it will be impossible to make a water-tight connection.
However, if you have easy access underneath the bathtub, it may be easier to first connect the drain assembly to the tub, install the tub, and connect the plumbing to the house as a final step.
Step #5 – Set the Bathtub
Now that the drain assembly is in place, apply silicone to both sides of each drain gasket. Then, slowly lower the bathtub into place, being careful not to smear the silicone sealant.
Then, put another large bead of silicone on the underside of the drain flange and then screw in the drain to the threaded elbow. Then put on the cover plate for the overflow drain. Wipe away any excess silicone before moving on.
Step #6 – Secure the Bathtub
Now that the tub is in place, re-install the 2×4 stud that you removed earlier to remove the old tub. Then, using 1 5/8″ lathe screws, secure the bathtub to the stud – one screw at each stud location and 2 -3 on the side tub flanges.
You’ll want to pre-drill the screw holes in the tub using a 3/16″ drill bit before screwing in the tub. And, make sure to use wood shims between the tub and the wall wherever there is a gap to avoid snapping the tub flange.
Step #7 – Test for leaks
Before installing tile or any finish material around the tub, you’ll want to make sure it isn’t leaking. So, wait about 24hrs for the silicone sealant to set, then fill the tub with water and listen carefully for leaks. If there is a leak, you’ll probably hear a faint dripping sound. If there is a floor below the bathtub, go there and listen for leaks and observe the ceiling for signs of water.
Step #8 – Caulk the Front Edge of the Tub
If there are no leaks, you’re almost done. Now, using a silicone sealant that matches the color of your tub, caulk the front edge of the bathtub where it meets the ground. This is to keep water that drips over the front edge of the tub from getting underneath the bathtub and causing mold growth.
And that’s it!
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Great videos – love the detail. We need to replace a tubs with a new tub and surround. We want to hire someone but are having a ridiculous time trying to get companies to quote the job. We have been through 2 contractors that were both no shows and did not bother to call. I will not work with someone that cannot make a courtesy phone call. Here is my question and sorry for taking so long to get to it. We are located in northern IL – Lake County. Would you be able to make any recommendations on companies that would provide an estimate, show up and do a quality install/job? Thanks for anything you can do to help us out.
home advisor
Home advisor may work in large metropolitan areas but where I live in rural Maine, it’s next to useless as most local contractors either don’t have websites or aren’t even tracked by sites like home advisor or even search engines like google. Weird I know but true. I had the same problem with roofing contractors not showing up or returning calls(even the ones that were linked with home advisor).
Why do you use the Delta Classic 400 and what type of tube would you recommend? Thanks
I am curious… As I’m looking around it sounds like I should be putting plaster Paris under the tub, however I noticed that you didn’t on this particular bathtub. Is that because of the under support that is built into it? Or do I still need to use plaster Paris for this particular tub, however I noticed that you didn’t on this particular bathtub. Is that because of the under support that is built into it? Or do I still need to use plaster Paris for this particular better?
I watched your video on removing and installing a bathtub very helpful.
Do you do this and were are you located
I live in Sacramento California, I am looking for someone to remove a walkin tub and replace it with a regular tub. Is this something you do, or can you recommend someone? I would need an estimate.
Hi, I just watched your video on installing a bathtub and I wanted to thank you for making that job look far less intimidating than I first thought it would be. I have one question that is pretty lengthy. I had a tub given to me that I would like to install without having to replumb the entire thing. My problem is that my current tub is right drain and the new one is left drain. I was wondering if it would be a good Idea to raise my floor with a bit of 2×4 framing and subfloor and just extend the drain under the tub to the original pipe on the right side. You see, my house is very old and all of the main piping is old black pipe. Replacing all of that myself seems to be a really daunting job and so I though if I could apply my idea of extending the drain under the tub to the main pipe could save me a lot of time, hard work, and money. I am sort of on a budget otherwise I would just hire someone. Thank you in advance for any advice you can provide me.
I would find a tub that is made the space. Doing a job like this is a sure sign of DIY, which is not helpful when reselling your house. Not only that, you’ll likely run into issues.
I loved your video and almost attempted to replace a fiber glass enclosure, to a regular bathtub. Is this something you do as a profession and what would be the cost, also where are you located. You seem to do so much more than I have seen in other videos. I am in a condo and don’t need any leaks on my neighbor. Thanks in advance.
I got the tub you used and am trying to find the proper bathtub drain assembly. I clicked on the link you have but it just takes me to Amazon but doesn’t specify one in particular. The specs for the tub say I need Drain and Overflow assembly (fits a 16-1/2” deep bathtub and 13 7/8” Drain to Overflow).
Most of them will fit; make sure to find the correct pipe diameter and check with the tub manufacturer directions (some Kohler tubs require special drains.)
After removing the tub the old drain assembly is intact and attached to the plumbing is it possible to reuse it? If not where and how to do I detach the old assembly?
It probably won’t line up with the new tub, so no, you probably can’t use it. Since the joints are glued together for the drain pipe, try to detach it somewhere that gives you the ability to easily attach the rest of the assembly. You want to leave about an inch of clean pipe to glue the new assembly to.