Steam Showers at Home: What It Takes to Build One

A steam shower is a sealed shower that doubles as a small steam room. A generator outside the enclosure boils water and pipes steam in through a head near the floor, and the glass, walls and ceiling hold it in. The part people see is the glass and a control panel. The part that matters is the construction behind the tile, because steam gets into places shower water never reaches. This page explains what it takes, so you can decide early whether it belongs in your plan.

What a steam shower adds to a regular shower

The generator

The generator is a small electric boiler. It needs a water supply, a drain connection for flushing, the electrical supply in its manual and a location within the maximum distance its maker allows from the steam head. Generators are sized by the volume of the enclosure and by what the walls are made of, because stone and tile absorb more heat than other surfaces. The manufacturer's sizing chart, not a rule of thumb, decides the model.

Put it where it can be serviced: in a vanity, a closet on the other side of the wall or another accessible space. A generator buried behind finished drywall is a future repair bill.

Walls and ceiling built for vapor

Water runs down walls. Steam is a gas under slight pressure and heat, and it pushes into every pore and joint. The TCNA, which publishes the tile industry's installation methods, has specific steam room methods in its Handbook, SR613 and SR614 (SR614 is the thin-set method over cement board), and gives several cautions:

• Use a waterproof membrane meeting ANSI A118.10 that is "rated and recommended by the manufacturer for the steam room application." Not every shower membrane is.
• "While glazed tile is vapor impermeable, the grout is not." Some manufacturers require the waterproof membrane on the face of the wall and a vapor membrane on the back, and insulating the wall cavity may be necessary.
• "In general, the industry cautions against the use of gypsum wallboard in a steam room environment."

The ceiling is the surface most often underbuilt. It has to carry the same steam-rated membrane as the walls. Many designs slope the ceiling so condensation runs to the walls instead of dripping on you; the slope, and any vapor retarder, follow the membrane or generator maker's steam-rated system instructions. The waterproofing explained page covers how membrane systems differ.

The enclosure and door

Steam escapes over the top of a normal shower door, so a steam enclosure runs glass to the ceiling, with a door that seals on all sides. Some designs include a small operable transom at the top to let steam out after a session.

Glass in walls or enclosures of steam rooms is a hazardous location under the Washington Residential Code (R308.4.5), and doors and enclosures for steam rooms must be safety glazing tested to the federal standard 16 CFR 1201. Details are on safety glass and shower doors, and the glass styles are compared in shower glass and doors. Heavy, full-height panels need solid blocking in the walls and ceiling for the hardware.

Electrical and permits

The generator's installation manual specifies its electrical supply, and it usually needs a dedicated circuit run by an electrician under an electrical permit. The control panel, lighting inside the enclosure and any fan add to the plan. Washington adds its own rules for electrical equipment and lights near showers, including GFCI protection for fixed equipment with exposed grounded metal parts within an enclosed shower area (WAC 296-46B-210). See bathroom electrical code and electrical permits.

A steam shower also changes the house's electrical load, so the electrician should confirm the panel has room for the new circuit before the generator is chosen.

Ventilation

Washington requires an exhaust fan in every bathroom (WAC 51-51-1505), and a steam shower releases a large amount of moisture into the room when the door opens. The Home Ventilating Institute suggests a separate fan for steam rooms. Plan a fan that runs automatically after the steam cycle ends, and keep the fan out of the sealed enclosure itself unless the generator maker allows it. Bathroom ventilation explains how to size and control it.

Materials that tolerate steam

• Porcelain tile is dense and does well. Grout is the weak point; a high-performance or epoxy grout and a steam-rated membrane behind it address that.
• Natural stone works but needs sealing and care in the heat. Marble and limestone etch with acidic products.
• Large panels and slabs reduce grout joints, which helps in a steam room.
• Bench: a built bench, wrapped in the same membrane, with a solid top that slopes to drain.
• Steam head location: low on the wall, away from the bench and where feet and legs will be, since the steam comes out hot.
• Avoid wood, painted surfaces and gypsum products inside the enclosure.

What it costs

In JDI Construction's published planning ranges, a steam shower system is an $8,000-$15,000 add-on to a bathroom remodel, on top of the base range for the room. The enclosure size, the generator and the glass move it within that range. The base ranges are on the bathroom remodel cost page, and the bathroom cost calculator lets you add a steam system to see a planning range for your room.

Decide these before design is final

• Enclosure size and ceiling height, which set the generator size.
• Generator location and its service access.
• Membrane system rated for steam, for walls, ceiling and bench.
• Glass to the ceiling, door type and any transom.
• Electrical capacity and the generator's circuit.
• Fan location and controls.

A steam shower is often planned as part of a spa bathroom plan. JDI Construction designs it as part of the whole room, so the generator, waterproofing and glass are specified together before demolition. Start on our Vancouver shower remodeling page.