A Practical Guide to Adding a Steam Shower to Your New Build

Where will the steam generator go?

The generator lives outside the steam shower, as close to it as practical, and never inside it. The limit is 60 feet of separation between the generator and the steam shower, and a 30-foot control cable comes in the box, with a 60-foot cable available. On a new build, the usual homes for it are a linen or utility closet, the inside of a vanity, the cavity of a sealed bench, a heated attic, or the basement mechanical area. Wherever it goes, leave a way to reach it, because someone will need access for service.

Size affects where it fits. A standard MS generator is about 14.5 by 14.75 by 6.75 inches, roughly the size of a briefcase. The larger MAX generators (MX4, MX5, and MX6) run about 28 inches wide and should not go in a vanity or any other tight space.

What electrical rough-in does a steam shower need?

A dedicated 240V circuit is standard, with 208V in some homes, sized to the generator you choose. The draw scales with capacity, from 21 amps for the smallest MS generator to 125 amps for the largest MAX. Size the generator first (next section), then let the electrician size the circuit to it.

What plumbing rough-in does it need?

Plan three connections: a water feed to the generator, a steam line from the generator to the steam head, and a drain from the generator. The piping has to be brass or copper; PVC and PEX aren’t rated for the job. Standard sizes are a 3/8-inch NPT water feed, a 3/4-inch NPT steam line, and a 1/2-inch NPT drain (1 inch on MAX generators).

Give the steam line a slope of 3/4 inch per foot, running either toward the steam head or back to the generator, so condensate has somewhere to go instead of sitting in the line. Insulate long runs. Where possible, add a pressure-reducing valve that holds incoming water between 15 and 25 PSI. Keep the generator drain and the drip-pan drain plumbed separately.

Where do the control, steam head, and bench go?

Size it to the room’s adjusted volume, not its raw dimensions. MrSteam’s SmartSizing method does this in three steps, and your blueprints already hold every number you need, even before the shower is built.

1. Measure. Multiply length by width by height, in feet, to get the room’s base volume.
2. Adjust for materials. Ceramic or porcelain tile needs no change. Natural stone, marble, glass block, or concrete pull heat out of the room faster, so multiply by 1.5. Acrylic holds heat, so multiply by 0.6.
3. Adjust for ceiling height. Up to 8 feet needs no change. Between 8 and 9 feet, multiply by 1.15. Between 9 and 10 feet, multiply by 1.3. Match the final number to the generator chart.

Here’s how much the finish choice matters on the same room:

Getting it right matters in both. A generator that’s too small can’t bring the room up to temperature, so sessions feel weak and the homeowner assumes the product is at fault. One that’s too big costs more up front and needs a larger circuit than the room calls for. MrSteam’s VirtualSpa runs the SmartSizing math for you and produces the technical specs you’ll need when ordering.

Every system comes down to four layers: a generator, a control, a steam head, and optional therapies and accessories. Here’s the current lineup for each. Several products named in the 2019 version of this guide are no longer mad and they’ve been replaced below.

Controls

MrSteam makes four residential controls today. The control drives both the experience and the price, so match it to the buyer you’re building for.

Steam heads

• Aroma SteamHead: square, with a well for a few drops of essential oil.
• Aroma Designer Finish SteamHead: solid brass, round or square, in 13 finishes.
• Linear SteamHead: flush-mounted in 16-inch or 27.5-inch lengths, and it nearly disappears into the grout line. It’s for residential use only, not for acrylic or fiberglass enclosures, and MAX generators need two. New-build note: it installs between two studs 16 inches on center, so frame for it before the drywall.

Steam therapies

These turn the steam shower into a true spa experience, and two of them need rough-in work that’s far easier with the walls open.

• AromaSteam (scent): a pump that meters fragrance into the steam line. It works with the iSteamX and TempoFlex; the iTempo and TempoTouch use the steam head’s oil well instead. Not for acrylic or fiberglass rooms.
• ChromaTherapy (light): LED mood lighting through a recessed ceiling fixture, controlled from the iSteamX or TempoFlex. It needs a 4¼-inch ceiling hole and must stay clear of insulation, so plan it before the ceiling goes up.
• AudioX (sound): a pair of wet-rated Bluetooth speakers that pair through the iSteamX. Each speaker needs a wall cutout and a 120V outlet.

Accessories

It’s most efficient to add these now rather than later, when installing them would disrupt the homeowner:

• AutoFlush: drains the generator tank after each use to cut down on scale. It fits MS90 through Super3 generators; AutoFlush MAX covers the MX4 to MX6.
• Drip pan: sits under the generator.
• Seating: a solid surface bench or a teak wall-mounted folding seat.
• Recessed light: a dimmable fixture rated for the steam room.
• SteamLinx: adds app and Alexa control on compatible generators.
• Remote Temperature Probe: required whenever the control mounts outside the steam room.

Towel warmers

Spa packages

Most residential projects start with a spa package, which bundles a control, steam head, and accessories for less than buying them separately. The current packages, from richest to simplest, are Bliss, XDream, XButler, ButlerFlex, Basic Butler, and Butler Touch, plus the Steam@Home package for compact spaces. Because they span budgets, one plan set can carry steam across several price points in the same community.

Seal it, waterproof it, and keep the steam where it belongs. A steam shower has to be a completely enclosed room, because any gap lets steam escape into the bathroom.

• Waterproof the enclosure with hot mopping, a closed-cell membrane such as Wedi or Schluter KERDI-BOARD, or a vapor barrier. The Tile Council of North America is the standard reference.
• An 8-foot ceiling is optimal, and a residential steam shower doesn’t need a sloped ceiling. The smallest comfortable room for one person is about 3 by 3 by 7 feet.
• Any window inside the steam shower should be double-paned, and light fixtures need to be steam-rated and vapor-sealed.
• For ventilation, put a standard exhaust fan outside the steam shower, in the main bathroom. A transom window helps steam clear after a session.

In new construction you choose the conditions. In a remodel you work around them.

With the walls open, you can put the generator exactly where service access is easiest, run a straight steam line at the right pitch, and pull a dedicated circuit sized to the generator. You can also frame for a Linear SteamHead, a ChromaTherapy fixture, and AudioX speakers before anything closes. In a remodel, each of those becomes a question of what the existing walls, ceiling, and electrical panel allow. That’s where the wireless TempoFlex earns its keep, since it skips the control wire run entirely. In new construction, any of the four controls is an easy run.

A licensed plumber and a licensed electrician, ideally ones who have installed MrSteam before. The plumber connects the water feed, the steam line, and the drain. The electrician wires the dedicated circuit and breaker.

Ready to plan the steam shower in your next build?

Size the system in MrSteam’s VirtualSpa, pull the specs from Residential Guides & Specs, or visit a dealer showroom to see the products in person. For the full planning picture, download The Ultimate Guide for Planning Your Home Steam Shower.