Short definition
A wet room is a bathroom where the entire floor and all walls are waterproofed (tanked). The shower has no curb or enclosure — water can splash, drip, or pool anywhere in the room without damage. Floor slopes to a drain (typically a linear trench drain) in the shower zone. UK origin; increasingly common in US modern and accessibility remodels.
What it is
The defining feature is whole-room waterproofing. Where a curbless shower waterproofs only the shower zone, a wet room waterproofs the entire bathroom — the principle being that any water that escapes the nominal shower zone simply flows back to the shower drain or evaporates from the tile surface.
Construction:
- Tanking. Liquid or sheet membrane (Schluter Kerdi, RedGard, Hydro Ban) bonded over cementboard or fiber-cement substrate across all floors and walls.
- Floor slope. 1/4 inch per foot in the shower zone (UPC 411).
- Drain. Typically a 2-inch linear / trench drain along one wall of the shower area.
- No shower enclosure. Optionally, a single glass partition deflects spray from the toilet or vanity, but no full curb or door.
WAC 51-50 / 51-56 require cementboard or equivalent (no greenboard) behind tile; tanking provides the waterproof barrier on top of the substrate.
Why it matters to a homeowner
Three homeowner cases drive wet-room remodels:
- Modern aesthetic. Wet rooms read European and contemporary. Large-format tile, slim linear drain, no glass — a high-design move.
- Aging-in-place / Universal Design. A wet room enables zero-curb shower access without a separate enclosure to navigate.
- Small bathroom. A wet room can make a tight space feel larger by removing the visual interruption of a shower stall.
Cost ranges:
- Wet-room remodel: $15,000 to $50,000+, significantly more than a standard bathroom remodel because of the extensive tanking, the drain placement, and the tile work.
- Per-square-foot tanking: $5 to $15.
The most common homeowner concerns:
- Toilet paper, towels, electronics get wet. Shower spray reaches farther than people expect. Many wet rooms add a slim glass partition (just enough to deflect spray, not a full enclosure).
- Drying time. A wet floor takes time to dry; bath mats and ventilation help.
- Cold floors. Heated tile floors are common in WA wet rooms — heat helps dry the floor and counters the cold-tile effect.
Common failure modes
- Inadequate tanking. Water reaches subfloor and framing; major rot remediation. Tanking quality is the single most important variable in any wet-room install.
- Insufficient slope. Water pools instead of flowing.
- Drain in wrong location or set too high relative to the floor. Pools.
- Shower spray reaches places homeowners don’t expect. Toilet, vanity, towel bar all get wet; sometimes the glass partition is the after-the-fact fix.
Common variants
- Wet room (entire bathroom waterproofed, this entry) vs. curbless shower (only shower zone waterproofed).
- European wet room (entire bathroom) vs. Japanese wet room (purpose-built bathing room — different culture, similar engineering).