What do I need for a steam shower?

The room decides whether the steam stays put. Mr. Steam's guidelines say the steam room must be completely enclosed, with full walls, a door, a floor and a ceiling, and that a gasketed door is recommended for heat sealing and steam containment. Other points from its list:

• Walls and ceiling must be water-resistant, noncorrosive surfaces such as tile, molded acrylic or fiberglass.
• The ceiling should be sloped so condensate does not drip on the person inside.
• A floor drain must be provided.
• No heating, venting or air conditioning devices go inside the steam room.
• Ceiling height should be limited to 8 feet.
• Windows that are part of the steam room should be double paned and tempered safety glass.

The 2024 International Plumbing Code adds that shower walls must be waterproof to at least 6 feet above the room floor, and that windows and doors within a shower enclosure must meet the safety glazing requirements of the International Building Code. Our page on the minimum shower size by code covers the basic shower dimensions.

The generator has to match the room. Mr. Steam's manual says correct sizing is important and that you find the total room volume by multiplying length by width by height. Its Steam@Home sizing chart pairs volume with model and material:

Mr. Steam says not to use a Steam@Home generator in a room under 60 cubic feet, and that a model rated for a larger room than yours may cause excessive temperature. It says rooms over 150 cubic feet, or built of natural stone, glass block or glass tile, or with ceilings over 8 feet, need its larger series. Those are one brand's model numbers, and its chart shows a tiled room needing a larger unit than a fiberglass room of the same size. Your installer will size from the brand they install.

The manufacturers' installation guides agree on the basics.

Location. Do not put the generator inside the steam room. Mr. Steam says to install it near the steam room, in a closet, vanity cabinet, or climate-controlled attic or basement, on a solid, level surface, upright, with at least 12 inches of clearance at both ends and the top or as needed for service. Kohler says the generator should be within 25 feet of the steam head, in a dry, well-ventilated area, and for best performance installed below the level of the steam head. Mr. Steam says not to install it or its plumbing where water could freeze.

Water feed. Connect a cold water line and provide a shut-off valve upstream of the generator. Mr. Steam recommends a strainer, and a pressure reducing valve to limit supply to 15 to 20 psig, an anti-water hammer device where required, and an approved backflow preventer as required by local codes. It says not to use PEX or PVC tubing for the water feed. Kohler calls for a 3/8 inch cold water line to a shut-off valve before the generator.

Steam line. Do not put any valve, trap or pressure relief valve in the steam line. Mr. Steam says the flow of steam must be unobstructed, and to use 1/2 inch brass pipe or copper tubing, insulate the line with pipe insulation rated for 250 degrees F or higher, and pitch it 1/4 inch per foot toward the steam head or the generator so condensate does not collect. Running the steam line down and then up creates a steam trap that blocks the flow.

Drain. The generator has a drain valve for service. Mr. Steam says to connect a drain line according to national and local codes and to check the local plumbing code for the receptor, trap and vent requirements. Kohler tells the installer to allow for a drain or spill pan under the generator.

Kohler says each steam generator requires a dedicated circuit and that all electrical work should be done by a qualified electrician. Mr. Steam says its generators connect to 208-volt or 240-volt power and that installation and service must be performed by qualified and licensed electricians and plumbers only. Do not wire it yourself.

Steam heads are hot and must go somewhere safe:

• Kohler says to locate the steam head 6 inches above the shower floor and 4.5 inches from the threshold, and to keep the steam control inside the enclosure so its sensors can regulate temperature.
• Kohler warns of scalding if the steam head is blocked or placed near a seat or bench, since the head is hot during operation.
• Mr. Steam's installation manual says to locate the steam head at least 12 inches from an adjacent wall or bench.

### Where do the control and the optional auto drain go?

The control has to read the room, not the steam. Mr. Steam's guidelines say to locate the control or remote temperature sensor where it senses general room temperature and not the direct steam emission from the steam head. For a remote probe, the guide says to mount it on a vertical surface 4 to 5 feet above the floor, in a spot representative of the temperature you want, and not above or near the steam head.

Mr. Steam also offers an optional AutoFlush feature that drains the generator after each use, after a time delay of about two hours so the water can cool. The guide says the unit drains by gravity, so a drain line lower than the AutoFlush assembly has to be available, and that plumbing must be done by a qualified plumber to national and local codes. If you want it, tell the plumber before the walls close, because the drain location is set at rough-in.

A steam shower combines water, drain, high heat and 240-volt power, in a room that traps moisture. It is a job for a plumber and an electrician, and it should be planned before the walls close. If you already have a shower, the manufacturers' rules about ceiling slope, sealing and glass may rule the space out. Our page on what is involved in converting a tub to a shower covers the plumbing changes that usually come first. If you are adding one during a bathroom remodel, see whether you need a permit to remodel a bathroom in Phoenix, since new fixtures and new plumbing lines are permit territory.

HQ Plumbing and Air is licensed and insured, takes emergency calls 24/7, and gives free estimates with an upfront price before work starts. See our plumbing services.