How do you install a freestanding stone bathtub?

What are the steps from floor check to first fill?

Who installs a stone bathtub, and who does what?

A licensed plumber handles the drain, trap, supplies and filler. A rigging or white-glove crew places the tub. A structural engineer signs off on the floor when the load is in doubt, and the builder or designer coordinates the order of trades. Aquatica recommends having the plumbing installed by a professional plumber.

Does the floor need reinforcing for a stone tub?

Often it does, and a structural engineer should make that call. A reference 67 × 31 × 22 in oval marble tub with 2.5 in walls weighs about 1,150 lb empty and about 1,960 lb filled with a 200 lb bather. Spread over its footprint that is roughly 170 psf, against the 40 psf live load typical of residential floors. See the weight guide for the full model.

Stone Forest states that the floor must be flat and non-deflecting when its tub is installed and that it cannot make recommendations on floor structure. For its molded stone tub, Aquatica asks for floor support rated for a minimum of 1,400 lb.

How is the drain roughed in before the tub arrives?

The drain is installed first and the tub is lowered onto it. Kohler has the installer extend the drain pipe a set height above the finished floor, and that height is model specific: its table runs from 1/2 in for some freestanding baths to 2-1/8 in for another. Ask for the tub's dimensioned drawing and give it to the plumber. Our quotes give exact dimensions and weight.

Aquatica recommends access from the floor below so the plumber can connect piping easily. Its guide also says to confirm the space is clear of pipes, joists, heating ducts and wires before cutting the floor, and to call a building structure expert before cutting any joist. The minimum trap for a bathtub is 1-1/2 in under the IRC trap-sizing table. See the drain and filler guide for fittings and code basics.

How do you set, level and seal the tub?

Kohler builds a platform of two stacked 6 ft 2x4s on each side of the drain pipe, lifts the bath onto it with straps and helpers so the drain sits over the pipe, then removes the supports and sets the bath down. Check for level and add shims where needed. Do not slide a stone tub across a finished floor.

Aquatica leaves a slight clearance of 1/8 in between the finished floor and the apron when leveling. For tubs set without access below, it raises the tub 3-1/2 in on 4x4 lumber so the joints can be tightened from beneath, then lowers it slowly. Sealing is separate. Kohler calls a silicone bead at the base optional, while Aquatica requires silicone that fully penetrates beneath the apron rim so water cannot seep underneath.

Should the base of a stone tub be sealed to the floor?

It depends on the maker and the base design. Kohler says to apply a thin, continuous bead of clear or color-matched silicone between the bath and the finished floor if desired. Aquatica says its silicone joint must reach under the apron. Use a stone-safe sealant; the care guide covers sealants and cleaners.

How do you fit the filler?

Waterworks floor-mounted fillers need hot and cold supplies roughed in at a fixed spread with blocking beneath the floor to anchor the legs. For one model the spread is 5-7/8 in on center and not adjustable, with 2 x 10 blocking. Waterworks also tells installers to check the tub measurements so the spout projects far enough into the tub, which matters over a thick stone rim. Kohler says to install the faucet valve and trim per the faucet maker's instructions.

How do you test the tub before the room is finished?

Close the drain, fill the tub to the overflow and inspect every drain connection for leaks. Aquatica also lets the tub drain and checks the joints from below. Run it with the plumber present, while the floor and ceiling below are still open.

Plan the route early. Kohler warns that its bath will not easily fit through doorways, and a stone tub is heavier still. The delivery guide covers measuring the path. For tub choices, browse the bathtub collection or the bathtub sizes guide.