Bathtub installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What bathtub installation is

Bathtub installation removes an old tub and sets a new one, then connects the drain, overflow and faucet and repairs the surrounding walls and floor. It is a larger job than a faucet change, because the tub's weight, the drain, and the wall waterproofing all have to be right.

Signs you need it

  • The old tub is cracked, has a damaged finish that cannot be restored, or leaks through the drain or the overflow
  • The tub is the wrong type for the room, such as an alcove tub where you want a freestanding tub
  • The overflow drain is clogged or leaking, and the tub cannot be fixed without removal
  • The surround and wall are water-damaged, which means the tub has to come out to repair them
  • You want a larger or deeper tub, or a tub with a different drain and faucet layout

What the pro does

  • Remove the old tub, the surround and the drain assembly, and inspect the subfloor, studs and the drain for rot and leaks
  • Set the new tub level on a solid base, and check the floor framing is strong enough for the tub when it is full
  • Install the drain assembly, the overflow and the trap with the correct slope and gaskets
  • Connect the faucet, the spout and the supply lines at the correct depth, and check the valves for leaks
  • Install the wall board and waterproofing around the tub, and seal the tub edge to the wall
  • Fill the tub and run the drain and the overflow under water before the walls are finished

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Tub type: alcove, drop-in, freestanding and corner tubs each change the mounting and the wall work
  • Tub material and size, which affects the weight, the drain fit and the framing needs
  • Subfloor and framing condition, and any rot that must be repaired before setting the tub
  • Whether the drain, the overflow and the trap are replaced or reused
  • Faucet and valve type, and whether the supply must be moved
  • Wall and tile work needed around the tub, including waterproofing and finish

What a written quote should spell out

  • Tub model, type, size and material
  • Drain assembly, overflow and trap, new or reused
  • Faucet, spout and valve, and whether the supply lines are replaced
  • Waterproofing method and materials used at the wall and tile
  • Subfloor or framing repair, if needed, and who handles it

Questions to ask before you hire

  • Will the tub fit through the doorway and into the space, and who moves it in?
  • Is the subfloor strong enough for the tub when it is full of water?
  • Will you replace the overflow and the drain assembly?
  • What waterproofing do you use around the tub, and do you test it?
  • Do you test the tub with water before the walls are finished?
  • Who handles the tile or surround, and is that part of your work?

Red flags

  • Pro who sets the tub on an uneven or soft floor without checking the framing
  • Pro who does not replace or check the overflow and drain when they are old or leaking
  • Pro who closes the wall before a water test of the drain and overflow
  • Pro who seals the tub edge with caulk only and skips the waterproofing behind the wall

What you can do yourself

A homeowner can clean a tub drain, replace a stopper, or reseal a tub edge with a bathroom caulk. Call a pro for any tub removal, any new drain or overflow, or any work behind the wall, since a leaking drain or overflow can rot the floor and framing below the tub without being seen.

Licenses and permits

The plumbing portion of a tub install, including the drain, overflow and supply, is commonly licensed plumbing work. Framing, wall and tile work may be done by other licensed or trained trades, so check with your state or local licensing agency.

Bathtub installation questions

How do I know if the floor under the tub is soft?

Press on the floor around the tub and check for spongy spots or a musty smell. A pro checks the subfloor and framing once the old tub is out, before the new one is set.

Can a tub be installed without removing the old one?

Sometimes, with a tub liner or a drop-in replacement, but the old tub has to be fully checked first. A pro can tell you whether the tub can be left in place or must come out.

Why does my tub drain leak after install?

A missing gasket, a drain that is not tight, or a trap that is not level are the usual causes. Test the drain with water before the walls close, so the leak is found early.

Should I replace the overflow when I install a new tub?

Yes, if it is old, cracked, or hard to seal. The overflow is hidden once the tub is set, so it is easiest to replace now.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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