Installing Your New Bathroom: Bathtubs

HOME   Bathrooms   Kitchens

The tub is the hardest of all bathroom fixtures to install, for the same reasons it is the hardest to remove: It is big, clumsy, and heavy, and you almost always have to make some plumbing attachments ‘in the wall. Because of the weight and bulk of even a fiberglass tub, you will need at least one assistant. If your tub is cast iron, you will need at least two helpers. The tub itself rests on the room’s subfloor, so it goes in place before you install your surface floor. You generally attach the supply and drain pipes after the tub is in position. The faucet, spout, and shower fittings go in when the walls are finished.

There are all sorts of bathtubs, made of different materials and varying in size and configuration. Each has its own peculiarities of installation, and you should be sure to get printed installation instructions from your dealer or the unit’s manufacturer. The instructions that follow apply to the most common enameled steel fixture 30 by 60 inches. But even if yours is a different sort of bathtub, these instructions should provide you with a general sense of the procedures you will have to follow.

Tools: dolly; wrench; screwdriver; hammer; drill; caulking gun.

Supplies: 2 by 4 supports for built-in tub; common nails; shims (it necessary); roll of fiberglass insulation; two to three 1 by 4 runners. 3- to 4-feet long; fittings and hardware; caulk; plumber’s putty; joint tape or joint compound.

1. If your tub does not come with a blanket of padding or insulation attached to its base, buy a single roll of fiberglass insulation at your home improvement center, and cut a section to fit against the sides of the fixture. The insulation cuts down bathtub noise and also helps the fixture hold heat longer. If there’s enough space, you can put insulation under the tub as well.

2. Built-in tubs require 2 by 4 sup ports along the walls for the tub’s flanges to rest on. Sometimes you can use the supports already in place from a previous tub, but you must measure heights very carefully. If there is any discrepancy, replace the supports. Otherwise your tub will never rest at a proper level. When the 2 by 4 wall sup ports are in place, lay a few 1 by 4 runners where the tub is to go, and push the tub along these runners until it is in place. Then ease the runners out one at a time.


3. Steel tubs can simply rest on the 2 by 4 supports, but the flanges of fiberglass tubs should be nailed to the supports. If the tub’s manufacturer has not predrilled holes in the flanges, drill your own pilot holes before nailing to prevent the fiberglass from splitting. If necessary, shim the flanges so that your tub is not only level, but also stable. It should not rock. If for some reason you find it impossible to level the tub perfectly, at least arrange for it to tilt toward its drain end, or you’ll al ways have to bail it out after use.

74b Fiberglass tub; Stud; shim to level tub


Sunken tubs conjure up images of resplendent luxury, but it is rarely practical and almost never easy to sink a tub in the course of remodeling a bathroom yourself. Filled with water, a tub can easily weigh a ton, and it must be supported. Ordinarily, the floor joists provide the primary support for a tub. To sink a tub, you must sever several of these stout timbers, build a new frame for the tub, and construct some additional support for the floor.

1. A basic tub enclosure is simply a frame made of 2 by 4s with sup porting studs placed every 16 inches. Build one frame for each of your tub’s exposed sides. The frames should be just enough lower than the rim of the tub to accommodate the combined thick nesses of a plywood covering and your chosen finish material. For example, if you want to finish the frame with tiles, which are generally ¼-inch thick, you would build your frame the height of your tub less ¾-inch— 1½-inch for a plywood covering and ¼ inch for the tile. When you cut the studs, remember to subtract an additional 3 inches to accommodate the top and sole plates. When your frames are constructed, attach them to the walls and floor with nails and white construction glue. Use toggle or molly bolts at the wall if your frame does not abut a stud.

2. To extend the storage ledge on any exposed side of your tub, merely build an extra frame identical to the first one, and set it parallel to the first frame as far away as you want your ledge to be wide. If you want a ledge wider than 16 inches, build another frame, and space the frames evenly so your ledge has adequate support at all points.

3. Cover the tops and sides of your frames with ½-inch CDX plywood or waterproof wallboard. Caulk all junctures of tub and frame. Complete with your chosen finish material.

However, with a little ingenuity you can create the feeling of a sunken tub by raising the level of the surrounding area rather than lowering the fixture itself.

Tools: hammer; screwdriver; circular saw.

Supplies: 2 by 4s to size; common nails; finishing nails; toggle or molly bolts (if necessary); ½-inch CDX ply wood or waterproof wallboard; white construction glue.

76 To create a wider ledge, build a frame parallel to the first; Cover frame with ½-inch CDX plywood or waterproof wallboard

To create a wider ledge, build a frame parallel to the first; Cover frame with ½-inch CDX Plywood or waterproof wallboard

Next: Installing Vanity Cabinets

Prev.: Installing Shower Stalls

top of page   Home


Updated: Thursday, 2011-06-23 19:07