Some whirlpool tubs or spas have a finished side or two, so framing and finishing the side panel are not required. Rectangular models install much like a standard tub, except that a GFCI electrical receptacle is required. Triangular whirlpools fit into a corner.
If the whirlpool has an integral spout, follow the manufacturer's instructions for running supply lines to the unit.
Large whirlpools are heavy when filled with water, so you may need to strengthen the floor by adding joists. Check the whirlpool's instructions and local codes.
Ideally, it's best to lay flooring after the tub is framed and installed but before any tiling is done.
Two or three days to frame, install, and tile a whirlpool tub
Carpentry tools, groove-joint pliers, PVC saw, wiring tools, tiling tools, putty knife, screwdriver, adjustable wrench
Connecting PVC pipe, basic carpentry, basic wiring, installing tiles
Measure the space carefully, taking into account the framing, backerboard, and tile thickness
Whirlpool tub, waste-and-overflow unit, lumber and screws for framing, GFCI receptacle, cable, breaker, cement backerboard with screws, mortar mix, tile, mastic, grout, caulk, spacers, pipe-thread tape, rag
Build a frame following manufacturer's directions. It's especially important to get the height right. You may snug the whirlpool up against one, two, or three walls. Where you snug the tub against the wall, attach a 2x4 ledger as you would for a standard tub. Where you will install tiles, plan the framing carefully, taking into account the thickness of the backerboard and tile (Steps 2 and 11). Most whirlpools require access to the plumbing at one end and the pump motor at the other end; check the manufacturer's directions.
Cut several spacers 1/8 inch thicker than the tiles you will install. (For 1/4-inch-thick tiles, cut pieces of 3/8-inch plywood.) Set the spacers on top of the backerboard wherever there will be tile. Set the whirlpool in place and see that it fits. Be sure the bottom of the tub is at the correct depth so it will rest on the mortar bed (Steps 7 and 8).
Test-fit the whirlpool to see that the waste-and-overflow unit will slip into the drain trap. Remove the whirlpool. Screw 2x2s to the floor around the drain hole to keep mortar out of the hole. In a bucket or wheelbarrow, mix water with dry mortar mix. The mortar should be just wet enough to be poured. Smooth enough mortar onto the floor to support the bottom of the whirlpool.
Place spacers (Step 3) on the backerboard atop the side-panel frame. With a helper, gently set the tub in place. Guide the waste-and-overflow into the drain trap but do not tighten the connection. Push down on the tub until the lip rests on the spacers, but do not press hard. Allow the mortar to harden overnight.
Apply thinset mortar using a notched trowel and set standard tiles on the side. When tiling the top edge, use bullnose caps for the outside corner for a finished look. After the thinset has dried, apply grout and clean the joints. Caulk the joint where the whirlpool rests on the tiles.
Once the wall is finished, remove the temporary nipple at the showerhead location. Wrap pipe-thread tape around the ends of the shower arm and screw it into place. Slip on the flange. Twist on the showerhead. Protect chrome with tape before tightening the showerhead with an adjustable wrench and groove-joint pliers.
Apply caulk around the spout hole. Choose a nipple of proper length for the spout and wrap pipe-thread tape around the threads on both ends. Thread the spout on by hand. Finish by wrapping the spout with a rag and tightening it with groove-joint pliers.