Installing an Alcove Bathtub
This common bathtub style is quite popular now for multiple reasons. Here’s what you need to know before buying and putting in a new alcove tub. In a new home build or a renovation, the bathroom is a major component, or you could want a total bathroom renovation. A bathtub is a big piece of that puzzle. Soaking tubs, tubs with jets, freestanding tubs, shower-tub combos, and many more options make bathroom personalization easy, but they make shopping and construction decisions hard. One of the most common and popular tub options is an alcove bathtub. This is what you need to know about alcove bathtubs.
Installing an Alcove Bathtub
The most exacting part of an alcove bathtub installation is the preparation of the alcove itself. Its dimensions have to match those of the tub within 1/2 to 3/4 of an inch. The floor must be solid and level. The walls must be straight. The wall studs must be spaced 16 inches on center. These exact specifications can be difficult to accomplish. You could be removing a tub from an existing alcove in an old house with funky framing and replacing it with a new tub. Just about any modern remodel in an old bathroom is likely to find surprises.
You can complete the installation of the drain piping, the water supply, and the tub faucet valve before or after you install the tub, but almost every plumber does it before to limit the time spent standing inside a brand-new bathtub and potentially damaging the finish. Although it isn’t required by code, it’s a good idea to provide an access panel for the tub valve in the back of the tub wall or in the wall in an adjacent closet or room. If you don’t do this and the valve has problems, you could end up having to break through the tub wall to do the repair.
An alcove tub is designed to be attached to three walls, so it only has one finished side, which is a solid apron panel that extends to the floor. The three open sides have flanges for securing the tub to the wall. This configuration allows the tub to be installed in only one direction, so you have to choose a right-hand tub, which has the drain on the right side, or a left-hand tub, the drain on the left side, based on the location of the plumbing pipes.
Your alcove tub may come with a built-in frame that has feet, which makes installation easier because the feet don’t require extra support, although you will probably have to shim them to level the tub. If you’re installing a tub without these feet and it’s made of heavy material, such as cast iron, you’ll probably have to set it in a mortar bed. This should be specified in the manufacturer’s installation instructions. Always read the manufacturer’s instructions carefully for a big project like this.
Once the tub is level, you’ve secured it to the wall and you’ve hooked up the plumbing, you have to finish the wall around the bathtub. The most reliably waterproof wall covering is a fiber cement board. When tiling or installing a shower in the alcove, you should use this or an alternative, such as foam board, provided the alternative is permitted by your local building authority.
Glass mat gypsum — which is the new greenrock (water-resistant drywall) — is the best choice if you want to paint the walls, hang vinyl wallpaper or install a fiberglass enclosure, and your building department may allow it even if you install a shower. Don’t even think of using conventional drywall.
How to Install an Alcove Bathtub
Warning! Shut off the water to avoid leaks and flooding. Have a partner to help you with installation. Bathtubs are 60 pounds or more, depending on the type of material.
Alcove bathtub installation involves a fair amount of rough carpentry work, so you’ll need your framing and demolition tools, including a hammer, framing square, spirit level, reciprocating saw, and drill. You’ll also need plumbing tools, which will include soldering supplies if the water pipes are copper. Miscellaneous supplies include hardwood or metal shims, one or two bags of mortar mix, 1-inch galvanized screws or roofing nails (depending on the bathtub material and construction adhesive), and 2- and 3-inch deck screws.
Position the tub into the installation opening and level the deck in both directions, shimming the base of the tub if necessary. Mark the final position of the underside of the deck by tracing a line onto the studs.
Remove the tub and attach a 1″x4″ stringer to the studs, with the top of the stringer touching the traced line. Never support the tub with its deck lip or stringers.
Install drain components into the tub following the drain’s installation instructions. The drain/overflow of the tub extends below the bottom of the tub.
If not already in place, prepare the in-floor drain. A 6″x12″ floor opening is required for the 1-1/2″ drain and waste overflow kit.
The tub must be supported along its entire bottom. Use 1-1/2″ to 2″ of mortar as bedding material. Do not use sand or foam.
After the mortar has been poured, and before it sets, position the tub within the recess until the rim is leveled against the stringers.
Nail the flange along the top of the tub rim to the surrounding studs, to secure the tub in place. Allow at least eight hours for the mortar to dry.
Proceed to the installation of flashing, drywall, or cement board to prepare for the installation of tile or tub surround.
South End Plumbing specializes in leak repairs and water heater installation, so remember, we are just a click away. We also specialize in tankless water heaters – give us a call! South End Plumbing is one of the only companies that will give you a free estimate. Call us at 704-919-1722 or fill out the form online to schedule a visit.