Tub to walk-in shower conversion: what it involves

What the project includes

A tub sits on a flat floor with the drain at one end. A shower needs a floor that slopes toward a drain, walls that are waterproofed from the floor to above the shower head, and a way to keep water inside. So the conversion is a rebuild of the whole alcove, not a swap of one fixture for another.

1. Remove the tub and the surrounding wall finish
2. Open the floor to change the drain and the supply lines as needed
3. Frame a shower base or, for a curbless shower, adjust the floor structure
4. Build the sloped floor and install the waterproofing
5. Set the tile and grout it
6. Install the valve trim, shower head and glass or curtain

The plumbing steps are where it can get involved. See our plumbing repairs page for the work we do on drains and supply lines.

The drain and the slope

A tub drains through a trap near one end. A shower drain sits in the floor, and the floor must fall toward it from every side so water does not stand. The plumbing code sets a minimum slope for shower floors, and the installer builds it into the mortar bed or the pre-sloped base. Where the drain sits matters. A center drain slopes four ways, a linear drain along one wall slopes one way and can allow larger tile.

If the new drain is in a different spot from the tub drain, the floor framing may need to be cut or notched, so it should be checked first.

Waterproofing is the real work

Tile and grout are finishes. They shed most water, not all of it. What keeps a shower from leaking into the wall and the floor below is the waterproofing layer behind the tile. It has to be continuous across the floor, up the walls, around the valve and the niche, and sealed at every corner and at the drain. Most shower failures start at a seam that was missed. Ask your contractor which system they use and how it is tested before tile goes on. Ask about water testing the pan. If the answer is short, keep asking.

Tile choices come after that. Our bathroom tile guide covers what to put on the floor and walls, and the tile contractor page covers the setting.

Curb or curbless

A curb is a low raised edge that keeps water in. It is simple to build and works with glass or a curtain. A curbless shower has an uninterrupted floor, which looks cleaner and is easier to step into, including for anyone who finds a tub edge hard. The cost of that is more structural work, because the shower floor has to sit lower than the bathroom floor so water still runs to the drain. That can mean lowering the framing between joists or building up the rest of the room. Ask for a site visit before you plan on curbless.

Glass, curtain and door width

A glass panel keeps the room open and shows off the tile. A frameless door looks clean but has hinges and clearances to plan for. A curtain is the lowest-effort option. Whatever you choose, think about the swing of the door, where the water hits and how you will reach the controls without stepping into the spray.

Permits and what to ask

Because the work includes plumbing and waterproofing, a permit often applies. Brentwood's published handout lists finish items such as tile as exempt but says tile inside tub and shower enclosures requires a permit. Concord's bulletin lists shower and tub enclosures among work that requires one. Other cities differ, so ask which office covers your address and who in the contract pulls the permit.

• What will you do about the drain location and the floor framing?
• Which waterproofing system do you use, and how is it tested?
• Curb or curbless, and why for this bathroom?
• Who handles the permit and inspection?
• What is included: tile, glass, fixtures, patching and paint?

Planning the rest of the bathroom

Many conversions are part of a larger bathroom plan, with a new floor, vanity and lighting. See best flooring for a bathroom, small bathroom remodel ideas and our bathroom remodeling page for the full project.

What goes wrong when it is done badly

Failures tend to show up later, not on the day the shower is finished. A pan that was never water tested can leak into the ceiling below. A floor with too little slope leaves water standing by the drain and grows grime. Waterproofing that stops short of the shower head height lets spray soak the wall above it. Grout that is the only barrier between the tile and the wall lets water through slowly.

The common thread is a missed step that no one could see once the tile was set. That is why the order of work matters, and why you should ask to see the base and the waterproofing before the tile goes on.

Tub to shower conversion: FAQ