Note that the alcove framing and plumbing, including the drain opening, must be finished before you fit and level the tub. Use the appropriate drill bit for whatever material the tub is made out of. For example, if it’s a fiberglass tub, use a bit meant for fiberglass. It’s as simple as that! Make the holes the same diameter as the screws you’re using to mount the tub on the studs. For instance, if you use #6 gauge screws, the diameter would be 3. 5 mm.
Thinset mortar is also known as tile mortar, so keep that in mind when you’re getting your supplies for this project. A 55 lb (25 kg) bag of mortar is enough for most standard-sized tubs, but you may need more if you’re installing a larger tub. If the mortar is too runny, you risk it spreading out too much and getting in the plumbing, which could clog it up and cause a lot of expensive problems!
If any of the mortar gets too close to the drain opening, scoop it away with a trowel and move it to another part of the subfloor.
The mortar spreads out a bit when you set the tub in it and level it, so that’s why it’s important to leave plenty of space around the drain opening.
Thinset mortar takes 24 hours to cure, so don’t rush through the next steps of leveling the tub. You have plenty of time to work!
Some tubs have adjustable feet that you can shorten or lengthen to raise or lower it in the front corners. You just screw them in or out by hand to adjust them. If you need to make any large adjustments, put wood shims under the edges of the tub to lift it higher out of the mortar in certain areas. Leave the shims there permanently—don’t worry, they’ll be hidden under the tub and won’t affect its sturdiness in the mortar in any way.
If there are gaps between the studs and the lip anywhere, place wood shims in the gaps and drive the screws through the shims into the studs to avoid damaging the tub’s lip.
Some mortar can take longer than 24 hours to cure. Refer to the manufacturer’s instructions for the mortar you used to be sure. After the mortar cures, you can proceed to install the tub drain, caulk around the edges of the tub, and perform any other work that needs to be done in the alcove.
The reason you measure both of these and add them to get the height of the tub is because you want the tub to be level at the height of the flooring in the bathroom. If you just measured the height of the tub, it would sit on the subflooring a bit below the finished floor. If the floor in the bathroom is already finished, you can skip the math. Just measure the height of the tub right now and measure up from the level of the finished floor in the next step.
If the bathroom flooring is already installed in the bathroom, you can instead measure only the height of the tub up from the top of the flooring near the corner of the alcove to make your mark.
This gives you a level line that the underside of the tub’s lip will be at in the alcove for the tub to be level.
If the studs in the alcove are not exposed, used a stud finder to locate them. The boards should be slightly shorter than the length and width of the tub, so they fit underneath the lip. If there is drywall over the studs, apply a bead of wood glue along the back of each ledger board as well to help them adhere to the wall nice and securely.
The tub should be supported by the ledger boards and the front edge of the tub should be flush with floor. If the tub has legs on the bottom, they should be sitting on the subfloor underneath it. If the tub has adjustable legs, screw them out or in by hand as needed for them to rest on the subfloor of the alcove. Lay your level along all edges of the tub and across the middle to verify that it’s completely level.
This only applies if the bathroom flooring is already installed. Otherwise, wait until it is to caulk around the bottom edge of the tub. If there is a finished wall behind the tub, apply a bead of caulk along the whole top edge of the tub’s lip as well to seal it. If you want to replace an old bathtub, check if the replacement tub fits your space well, and you can move it through all doorways. [15] X Research source Remove toilets or sinks that may be in the way. Disconnect the drain and the waste-and-overflow unit, and check if you need to replace any damaged parts. [16] X Research source Since tile damage is possible, you can purchase the replacement tiles beforehand and complete the work quickly.
