Tub-to-shower conversion: more than a fixture swap

Who should convert the tub, and who should keep it?

Convert when nobody bathes, when stepping over the tub wall has become a risk, and when at least one other tub remains in the house. Houzz's 2025 feature findings show only 27% of bathroom renovators upgraded a bathtub and 13% a tub-shower combination, and NKBA's 2026 survey shows 55% of designers prioritizing shower size over a tub. A conversion also suits a guest bath that serves mostly adults.

Keep the tub when it is the only one in the house and young children, dog washing or resale are in the picture. NAHB's 2024 buyer survey found 78% of buyers rate both a shower and a tub in the primary bath as essential or desirable. A house with no tub at all narrows the buyer pool. If the tub itself is the problem rather than bathing, a freestanding tub, which 45% of tub upgraders chose, or a walk-in tub are alternatives to removing it.

What is found when the tub comes out?

Almost always something. The subfloor at the drain end is soft from decades of a slow trap leak or overflow drips. The drain is a 1.5-inch tub line where a shower wants 2 inches, and it sits at one end of the alcove rather than where a shower base needs it. The walls behind the old surround are drywall or plaster with no membrane, sometimes with mold. The supply lines and the tub spout stub are in the wrong place for a shower valve. In older houses the tub is cast iron and weighs 300 pounds, which changes the demolition price.

None of these should surprise the pro, and the proposal should carry unit prices for each: subfloor per square foot, drain replacement per run, wall board per sheet. Houzz found 37% of renovators went over budget in 2025; in conversions, the tub-out surprise is the usual reason, and a written unit price turns it into an expected cost.

• Soft subfloor at the drain end
• 1.5-inch tub drain where a 2-inch shower drain is required
• Drain located at the alcove end, not the base's drain position
• No membrane behind the old surround; possible mold
• Valve rough-in at tub height, not shower height

What are the drain and base choices, and what do they cost?

The cheapest conversion keeps the drain where the tub's was and uses a prefab base made for that position (a 60-by-30 or 60-by-32 base with an end drain). Add an acrylic or solid-surface three-wall surround, a valve, and a framed door or curtain: $4,000 to $7,000 installed. The mid path uses a tile-ready base with the drain moved to center or a linear drain at the back wall, tiled walls over a membrane, and semi-frameless glass: $7,000 to $11,000. The top path recesses the floor for a curbless entry, uses large-format tile, a linear drain and frameless glass: $11,000 to $15,000 or more.

HomeAdvisor brackets a conversion at $1,500 to $8,000, with a walk-in shower averaging about $5,400, which matches the prefab path. Moving the drain on a framed floor adds $800 to $2,500; on a slab, $2,000 to $4,000. Upsizing the drain line from 1.5 to 2 inches is often required by code for a shower and should be a named line.

What does the new enclosure and entry look like?

A five-foot alcove gives you options a square shower does not. A fixed glass panel at the valve end with an open entry of 24 to 30 inches keeps spray in and needs no door, which suits older users and wheelchairs. A hinged door on a half-wall suits a tub-deep alcove with a window. A sliding door on a track is the least expensive glass option but the hardest to clean and the one that fails first. Houzz's 2025 data showed low-curb entries leading at 44% and curbless at 20%; a conversion alcove is the easiest place to build either.

Wall material follows maintenance tolerance. A three-piece solid-surface surround has three joints; tile has hundreds. NKBA found 89% of designers favor minimal grout, and large-format tile or slab panels are the middle path. Whatever the finish, a membrane goes behind it; a conversion that puts new acrylic over old drywall is the version that fails.

What is the sequence, and how long is the bathroom down?

Day one: tub out, surround and wall board removed to the studs, subfloor inspected and photographed. Days two and three: drain upsized and repositioned, valve moved to shower height, blocking installed for grab bars and glass, fan checked or added; inspection where required. Day four: base set or membrane and pre-slope built, flood test started. Day five: flood test checked, wall board and membrane. Days six through nine: tile or surround, grout, sealant, trim. Prefab conversions can finish in three to five days; tiled ones in eight to twelve, plus two to three weeks for custom glass.

In a one-bathroom house, the toilet and sink stay usable except during the day the tub comes out and the days the floor is open. This Old House's survey found 2 in 3 bathroom projects finish within four weeks; conversions are usually at the fast end unless the drain moves on a slab.

What are the mistakes specific to conversions?

Reusing the 1.5-inch tub drain, which drains too slowly for a shower and may not pass inspection. Setting a prefab base on an out-of-level subfloor without a mortar bed, so it flexes and the drain seal fails. Installing an acrylic surround over the old drywall with construction adhesive. Leaving the valve at tub height, 28 inches off the floor, so you bend to adjust it. Building a curb from stacked two-by-fours and tiling over them. Forgetting blocking, then adding grab bars into a surround with toggle bolts. Ordering the glass from the tub dimensions before the walls are finished.

The CDC's analysis of 234,094 emergency-treated bathroom injuries found about two-thirds in or around the tub or shower. The conversion removes the tub wall, which is the point; finishing it with a slippery floor tile or no place to put a grab bar gives some of that risk back. Nonslip tile and blocking cost almost nothing here.

How do resale and regional factors change the answer?

The resale rule is one tub per house. In a home with two full baths, which our analysis of the federal government's 2024 household survey puts at 46.8% of occupied homes (53.0% in the South), converting the primary bath's tub while the hall bath keeps one is the common and safe pattern. In a one-bath house, a conversion trades the buyer pool for daily use; for an older household staying put, that is often the right trade, but it should be a conscious one. The 2025 Cost vs. Value data credits a midrange bath remodel with about 80% recoup; a conversion within that scope shares in it.

Regionally, slab foundations across the South and West raise the cost of moving the drain, which favors the prefab-base path with the drain kept in place. Older housing brings cast-iron tubs and drains, which raise demolition and drain costs, and it is more often a one-bath house: our analysis of the EIA's 2024 survey found 36.6% of owner-occupied homes built before 1990 have one full bathroom against 7.0% of newer homes, a 29.7 points gap. The locations hub has the details, and the polls show what other households are doing with the tub.

How do you compare conversion proposals?

Require the base type and size, whether the drain is upsized and moved, the membrane system, the flood test, the wall material and what goes behind it, the valve model and height, the enclosure type, the blocking plan, the fan, and unit prices for subfloor and wall repair. A $4,500 proposal that reuses the tub drain and glues a surround to drywall is not the same job as a $6,500 proposal with a new 2-inch drain, a membrane and a mortar-set base. Ask each pro what they expect to find under the tub and what it costs if they do.

Use the tub-versus-shower comparison to settle whether the tub should go at all, the calculator to check the total, and the request form to send one brief to several independent pros. If the person using the room has mobility needs now or soon, the accessible page covers the dimensions a conversion should follow.