Turning a tub into a walk-in shower

A lot of Cape houses have the same bathroom: a five-foot alcove tub with a shower head over it, a curtain or a sliding glass door, and tile from whenever the last renovation happened. Nobody in the house has taken a bath in four years.

Converting that into a proper walk-in shower is one of the most common projects we do, and one of the most satisfying, because the room usually gets dramatically better without moving a single wall. It is also consistently underestimated, because from the outside it looks like taking one thing out and putting another thing in.

Why people do it

The reasons we hear, roughly in order:

• Nobody uses the tub. It is twelve square feet of floor doing nothing but collecting a soap dish.
• Stepping over a tub wall is getting harder. Either now, or with an eye on the next ten or twenty years.
• The existing surround has failed. A fiberglass unit that has gone yellow and flexes, or tile with cracked grout and a soft spot — which is often a leak that has been running for years. See the signs in the waterproofing article.
• The bathroom feels cramped and dated, and the tub is the reason.
• A guest or in-law bathroom where a shower is simply more useful.

Any of those is a good reason. What changes the project is which one it is, because "the tub is unused" and "the surround is leaking" lead to very different scopes once the wall is open.

Why it is not a swap

An alcove tub is a manufactured waterproof vessel. It arrives as one piece, it sits on the floor, and its own walls contain the water. The tile above it only has to handle splash, which is why a lot of tub surrounds get away with lighter construction for years.

A tiled walk-in shower has no vessel. The floor is built on site, water lands directly on it, and everything that keeps water out of your framing is an assembly someone constructs: a sloped pan, a waterproofing membrane, sealed corners, a correct drain connection. The whole subject of that article becomes load-bearing here in a way it was not before.

So the conversion is: remove the tub, remove the old surround and substrate, evaluate and repair whatever is behind it, build a properly pitched pan, install a complete waterproofing system, then tile. The tile is the last and least risky part.

The drain is the whole story

Here is the part that surprises people most, and it is the main reason a conversion costs what it costs.

A tub drain sits at one end of the tub, against the wall. A shower drain usually needs to be near the middle of the shower floor — or, for a linear drain, along one wall. Either way, the drain generally has to move.

Moving a drain means getting at the plumbing under the floor. How hard that is depends entirely on what is below your bathroom:

• Over a basement or crawlspace, the drain line is accessible from below. More straightforward.
• Over a finished room, reaching it means opening the ceiling below and repairing it afterwards. That is a real addition to the scope.
• On a slab, moving a drain can mean cutting concrete, which changes the project substantially.
• Joist direction and depth matter too. A drain has to slope, and the available depth between the subfloor and the ceiling below sets what is possible. Joists cannot be cut wherever is convenient.

This is why nobody can price a conversion over the phone, and why a site visit includes looking at what is underneath. It is also why "can we keep the drain where it is?" is a question worth asking — occasionally a layout can be designed around the existing location, particularly with a linear drain at the former tub end, and that can simplify things considerably.

The valve usually moves too. A tub-and-shower valve sits low with a tub spout; a shower valve sits at a comfortable height with no spout. That is a plumbing change with the wall open, which is the right time for it.

Curb or curbless

Two ways to finish the entry, and the decision has to be made before the floor is built.

A curb is the small raised threshold you step over. It is the conventional approach, it contains water reliably, and it works on essentially any floor structure. The tile wraps over it and down both faces, and the waterproofing has to wrap with it — an unsealed curb top is a direct path into the floor framing.

Curbless — a zero-threshold entry, where the shower floor is continuous with the bathroom floor — looks superb and is genuinely better for anyone with mobility concerns. It is also a more demanding build. The shower floor has to be recessed relative to the bathroom floor, which usually means modifying the floor structure, and that is not always possible depending on the joists and what is below. Curbless typically wants a linear drain, a larger wet area, and often a longer glass panel to keep water contained.

Both are good answers. What is not a good answer is deciding after the pan is built, because the floor structure, the drain and the waterproofing are all different.

Using the space you gain

A standard alcove tub is about five feet by two and a half. That footprint becomes a shower roughly sixty by thirty inches, which is a generous single shower — noticeably larger than the thirty-six-inch-square units a lot of people picture.

What to do with it:

• A bench. A real one at a comfortable height, which the five-foot length can accommodate. Benches hold water, so they get waterproofed as an assembly and pitched to drain.
• A niche, or two. Set into the wall at the height you actually reach for things, not wherever the studs happened to land. Worth deciding with the layout, because a niche is a hole through a waterproofed wall with several new inside corners.
• A glass panel instead of a full enclosure. On a shower this long, a single fixed panel often contains water adequately and keeps the room feeling open. It also means less glass to clean.
• The tile layout. A long wall is a good canvas, and this is where format matters — big tile on the walls for fewer joints, mosaic on the floor for slope and grip. That trade-off is its own article.

One caution on fixtures: a rain head mounted overhead and a hand shower on a slide bar are both popular and both fine, but each is another penetration through the waterproofing and the second one may mean a second valve. Decide on fixtures before rough plumbing, not after tile.

Planning for later

If part of the motivation is being able to use this bathroom in twenty years, there are things that cost very little now and are expensive to add later.

• Blocking in the walls for grab bars. Solid backing installed while the wall is open costs almost nothing and means a grab bar can be mounted properly, into structure, whenever it is wanted. Without blocking, a later installation is into tile and whatever is behind it.
• A bench, or at least the space for a seat.
• A hand shower on a slide bar, which is useful for a seated shower and for cleaning the shower itself.
• A wider entry than the minimum, if the layout allows.
• Slip resistance on the floor. Matte, honed or structured, and a smaller format for more grout lines. Never polished. Covered in the material article.
• Curbless, if the floor structure permits it.

Grab bar blocking is the one we push hardest, because it is the cheapest item on the list and the one nobody thinks of until it is behind finished tile.

The resale question

This comes up on nearly every conversion, usually as "will I regret losing the tub when I sell?"

The conventional wisdom is that a house should keep at least one bathtub, mainly for buyers with small children. We think that is reasonable and we are tile installers, not real estate agents, so take it as general sense rather than market advice.

The practical version: if the house has another tub in another bathroom, converting this one is an easy decision. If this is the only tub in the house, it is worth a conversation with someone who knows your local market — and on the Cape, where a lot of houses are second homes or rentals, the answer depends heavily on what the house is for. A year-round family home and a summer rental are different buildings in this respect.

If you are converting specifically to sell, the thing that sells is a shower that looks and feels well built. A cheap conversion reads as a cheap conversion to a buyer walking through, and a failed one shows up in an inspection.

Five decisions before demolition

1. Curb or curbless. It changes the floor structure, the drain and the waterproofing.
2. Where the drain goes, and whether it is a center or linear drain. This also decides what tile can go on the floor.
3. Bench, niche, grab bar blocking. All of them are framing and waterproofing decisions, not finishing decisions.
4. Fixtures. Valve height, rain head, hand shower. They are penetrations and they affect rough plumbing.
5. Glass or no glass, and roughly what kind. Glass is measured after tile and fabricated to the finished opening, so it has a lead time — see the timeline article.

Settle those five at the estimate and the project runs cleanly. Leave them open and each one becomes a pause mid-job, which is the most common reason a bathroom takes longer than it should.

Questions we get asked

Written from our own conversions on Cape Cod and the South Shore. What is possible in your bathroom depends on your floor structure, your plumbing and what is behind the existing surround — none of which can be assessed from a photograph. Resale comments are general observations, not real estate advice.