Tearing out a tub to install a separate shower used to be the default master-bath move, but the wet-room trend has reversed that thinking for a lot of homeowners. A well-planned tub in shower design places a freestanding or built-in tub inside a fully enclosed wet zone, eliminating the cramped tub-shower combo while keeping a bath option for selling later. Done right, this layout makes a 50-square-foot bathroom feel like a 75-square-foot one, but the waterproofing and drainage details have to be perfect.
Wet Room Layout Basics
A wet room is a fully tiled, fully waterproofed bathroom zone where the entire floor is the shower pan. The tub sits inside that zone, sometimes on a tile pedestal, sometimes free on the wet floor. Drains can be concentrated under the tub area or split between a tub drain and a linear floor drain near the entrance. Plan the floor slope at 1/4 inch per foot toward the drain, with the tub area itself sitting on a level pad if you’re keeping it dry inside the bath.
Tub Selection: Freestanding, Drop-In, or Alcove
Three tub types work in this layout, each with trade-offs:
- Freestanding — Soaking tubs from Kohler, Signature Hardware, or Wyndham at $900 to $3,500. Most dramatic visually. Plumbing routes through the floor.
- Drop-in — Set into a tiled deck. Looks substantial, allows ledges for shampoo and a glass of wine. Adds 8 to 12 inches of footprint.
- Alcove — Three-wall built-in. Most economical at $400 to $800 but loses the wet-room aesthetic.
Freestanding works best in master baths over 60 square feet. Drop-in suits family bathrooms where the deck doubles as a perch. Alcove fits smaller secondary baths where budget matters more than drama.
Glass Enclosure Options
The glass wall separating wet zone from dry zone defines the look. Three configurations dominate current design:
- Single fixed panel — A 36 to 48 inch glass panel partway across the opening, no door. Works if the bathroom is large enough that splash escape isn’t an issue.
- Pivot or hinged glass door — Full enclosure with a swinging door. Cleanest look but requires careful sizing for clearance.
- Sliding barn-door glass — Best for narrow openings under 60 inches. Rolling hardware costs $400 to $900.
Specify 3/8-inch tempered glass minimum, or 1/2-inch for any panel taller than 78 inches. Frameless glass costs more but reads as far more luxurious than framed alternatives.
Waterproofing the Right Way
This is where corner-cutting creates expensive problems. Skip a proper waterproofing membrane and you’ll see floor staining, ceiling damage in the room below, and mold within two years. The two reliable systems:
- Schluter-KERDI — Orange polyethylene membrane bonded to the substrate with thinset, then tile applied directly over it. Most popular among tile pros.
- Liquid waterproofing (Laticrete Hydro Ban or RedGard) — Roll or trowel-on coatings. Faster to apply, fully bonded to substrate.
Both work, both are warranted, and both fail if applied to dirty or unprimed substrates. Inspect the prep before tile goes down.
Floor Slope and Drain Placement
The floor must slope toward every drain. Linear drains along one wall give you a single-direction slope and look architecturally cleaner than center drains. Schluter-KERDI-LINE and Infinity Drain make 24 to 60 inch options at $300 to $700. If you’re using a freestanding tub, place the tub drain centered between two floor drains so water doesn’t pool around the tub feet. Confirm the joist layout supports the drain routing before tearing out the existing floor.
Heating: Floor Warming Is Almost Required
Wet tile floors stay cold year-round in most U.S. climates. Electric floor warming under the tile costs $5 to $9 per square foot and pays back in comfort every morning. The Schluter DITRA-HEAT system or Warmly Yours TempZone install in a thinset bed under tile and run on a programmable thermostat. Skip this and the room feels uninhabitable from October through April.
Ventilation Sizing
A combined tub-shower wet room generates significantly more humidity than a standard bath. Size the exhaust fan to 1 CFM per square foot of bathroom plus 50 CFM for any tub or shower over 60 inches in any dimension. A typical 60-square-foot wet room needs at least 110 CFM. Panasonic WhisperGreen and Broan ULTRA series fans run quietly at 0.3 to 1.0 sones and last decades. Always vent to the exterior, never into an attic.
Storage Inside the Wet Zone
Recessed niches solve the shampoo-and-soap problem without adding shelves that catch sight lines. Plan two niches: one at standing shower height (60 to 72 inches off the floor) for shampoo and conditioner, another at tub height (28 to 36 inches above the tub deck) for tub salts and a candle. Frame niches between studs at 14 inches wide and 12 to 16 inches tall, then waterproof and tile per the same membrane system as the walls.
Budget Reality
A tub in shower design wet room costs more than a standard bathroom remodel because of waterproofing, glass, and drain work. Expect $25,000 to $55,000 for a master bath conversion in most U.S. metros, depending on tile selection and tub price. The premium pays back at resale — wet rooms have become the headline feature in primary suite listings, and appraisers have started recognizing them as a value-add over traditional tub-shower combos.
Tile Selection for the Floor and Walls
Tile choice influences both safety and maintenance. For wet floors, specify tile with a Dynamic Coefficient of Friction (DCOF) of 0.42 or higher — that’s the ANSI A137.1 wet-area threshold. Small format mosaics 2×2 inches or smaller pack more grout joints per square foot, increasing traction and conforming better to a sloped pan. Larger 12×24 or 24×24 wall tiles minimize grout lines on vertical surfaces and look cleaner. Pick a porcelain rated for wet area use rather than a glazed ceramic, which can lose its slip rating after years of soap film accumulation.
