How To Install A Bathtub
Changing out your old bath tub to a new acrylic or fiberglass tub is not a super difficult job but it will be time consuming and really disturb your bathroom
The main problem with this job is that the tub will be mounted to the walls under the drywall which in turn is usually under wall tiles or tub surround panels. So you really are not just changing the tub you will be changing the tub, the wall covering (drywall & Hardi board), the tub surround and or tiles and possibly the tub faucet and floor covering in the bath room and more then likely you will need to paint. Needless to say this is a big job and you should be prepared to give it a lot of your time or it will drag on. If you are doing all of what I mention above I would expect it to take you at least 2-3 days. For this article I will be just be covering replacing the bath tub but you can find the other jobs that will be involved in other articles on this web site as well.
Difficulty Level: 7/12
- drywall saw
- utility knife
- screw driver set
- pry bar
- 24″ bubble level
- 12″ pipe wrench
- drain wrench tool
- bath tub
- bath tub drain and overflow set
- kitchen and bath silicone
- Hardi backer (cement board)
To start with you will want to remove as much stuff from the bathroom as possible to give yourself room to work. Take down any shower curtains or sliding shower doors.If your shower walls are covered by a plastic tub surround remove it completely. If your walls are tiled I would recommend removing and replacing all of them as well but you may want to just remove what you need to (approximately 30″ up from the tub) and try to find matching tiles to re-tile with after you are done the tub install. Next you will likely have a drywall layer which you will need to remove. Start by marking a horizontal level line on all of the drywall areas above the tub at about 28″ high from the top of your tub,then mark a plumb vertical line 1″ out from the front of the tub all the way from your horizontal line down to the floor. Use your drywall saw and cut along all of these lines and remove the drywall.
TIP: When cutting into a wall always be careful of hidden obstacles like electrical, plumbing.
You should find some rusted screw on clips around the top flange of the tub or screws through the flange, remove any you find. Check to see if your tub has a bead of silicone along the front edge where it meets the flooring. If it does, cut this carefully with the utility knife,trying not to cut into the flooring. Next you can remove the old drain and over flow pipes. The overflow is easy – remove the chrome cover that is partway up the drain end of the tub and sometimes there maybe 1-2 screws behind this as well. Now the drain, these can be tough to get started but finally will loosen up ,use your drain wrench tool and insert it down into the drain where it should fit onto the built in strainer, turn counterclockwise until it comes right out.
You may want some help now to lift the tub out and remove it from the room. To remove the tub you usually need to lift from one end to get it standing on end then it can be carried out.
TIP: If you are doing this by yourself, you may find using a two wheeled hand cart/trolley to move the tub out works well, just strap it to the cart and wheel it away.
Now that the old tub is gone remove the old drain and over flow pipes which are on the floor hooked into the main plumbing above the p-trap. Using the tub drain/over flow kit that you bought install it to the new tub as per the manufactures instructions. By measuring you can check to see if the existing p-trap position will line up with the new plumbing on the tub. Usually this will not line up so you will need to possibly cut some of the existing plumbing out and redo it to line up with new tub. Do not forget that there must be a p-trap on this line again to avoid having sewer gas escaping up the tub drain and into the house.
Your new tub may require a ledger board along the back wall to help support the tub. Use the manufacturers instructions to determine the height of this ledger or if it is required. Your old tub probably had one nailed to the wall that you may be able to remove and reuse. So now that the ledger and plumbing are in place you can lower the new tub into the space you have. Again you may want some help with this as it is very awkward on your own. I have damaged a couple of tubs trying to do this on my own and trust me after all this work you do not want to get another tub. Once tub is sitting in position use the level to check it for level.
TIP: Place the level on the upper deck top of the tub not down in the bottom of the tub as the bottom usually has been built with a sloping bottom for better drainage.
After you have leveled the tub by adjusting the ledger you can attach it to the wall studs w/screws in the pre drilled holes in the upper flange of the tub (do not over tighten screws). I would recommend #8×11/2″ stainless steel screws to mount the tub. If you plan on installing a new tub surround use Hardi backer board to fill in the missing wall areas and tape, mud, sand, prime and paint the walls then install the tub surround. But if you plan on installing all new wall tiles then you should remove the rest of the drywall up to a height 2″ below the expected height of the last row of tiles and then install the Hardie backer board to that area and follow with tape, mud,sand, priming and painting the walls. Then it is ready to tile.
Related bathroom articles: How to install a bathtub surround