What Is a Steam Shower and How Does It Work?
A steam shower is a fully sealed shower enclosure that fills with hot vapor on demand, turning an ordinary shower into a personal steam room at roughly 110 to 115°F and close to 100% humidity. The shower fixtures still work exactly as they always did.
It works by boiling water inside an electric generator hidden outside the shower, then piping that vapor in through a steamhead mounted low on the wall. A control inside the enclosure sets the temperature and the session length.
One disclosure before we get into it. We're an authorized Mr Steam dealer, so the specifications and prices below come from equipment we actually sell rather than generic ranges.
Jump to: What it is and isn't | The four parts | What happens when you press start | Why it feels hotter than it reads | What makes a shower steam ready | Where the generator goes | Sizing | Cost | FAQ
What a Steam Shower Is, and What It Isn't
A steam shower isn't a replacement for your shower. It's a normal shower with steam equipment added, so you can take an ordinary shower in it any day you don't feel like steaming.
It is a steam room, just built into a shower footprint instead of a standalone tiled room. Same equipment, same temperature, same saturated air, which is why the two terms get used interchangeably.
What it isn't is a hot shower with the door shut. A regular shower vents most of its humidity and cools as soon as you turn the water off, while a steam shower seals the enclosure and fills it with vapor from a dedicated generator that has nothing to do with your shower valve.
The point of it is heat therapy you don't have to leave the house for. You sit in saturated heat for 10 to 15 minutes, then rinse off in the same enclosure.
The Four Parts That Make Steam Happen
Three pieces of equipment and one piece of construction do all the work. Miss any one of them and the system either won't run or won't hold steam.
The steam generator
This is the appliance that does the actual boiling, and it lives outside the shower in a closet, vanity cabinet, basement, or insulated attic. It's about the size of a large briefcase, so it hides easily.
Inside is a copper heating element sitting in a small tank, plus electronic probes that read the water level. When you start a session, a valve fills the tank and the element brings that water to a boil.
Everything else in the system is plumbing and controls wrapped around that one job. Our Mr Steam MS 7.5 kW generator package is a typical residential example, and it bundles the generator with a control and steamhead so the parts are already matched.
Mr Steam MS 7.5 kW Steam Shower Generator Package with iTempo Control
The steamhead
The steamhead is the small outlet inside the enclosure where vapor actually enters the room. It mounts low, 6 to 12 inches off the floor, so steam rises and fills the space from the bottom up.
It goes on the wall with the faucets and away from wherever you sit. The steamhead and the vapor coming out of it are extremely hot, so putting it next to a bench is a mistake you only make once.
The control
The control is the panel you press to start a session and set temperature and time. It sits on the opposite wall from the steamhead, near the seating area, roughly 4 to 5 feet off the floor so it's reachable while you're sitting down.
Wired controls run a low voltage cable back to the generator, which has to be routed before the walls close up. Our ButlerTouch control package pairs a TempoTouch control with a Linear SteamHead and is the most common way people buy those two pieces together.
Mr Steam ButlerTouch Control Package with TempoTouch and Linear SteamHead
The enclosure
This is the part people underestimate. A steam shower needs a fully sealed, floor to ceiling enclosure lined with non-porous material, because the whole system depends on trapping vapor rather than letting it escape.
A standard shower with a gap above the door will not hold steam. More on exactly what has to change further down.
What Happens From the Moment You Press Start
Most explanations stop at "the generator boils water." Here's the actual sequence, because it explains a few things that surprise first time owners.
You press start on the control. An electric valve opens and fills the generator tank from the cold water supply, and the electronic probes tell the board when the right level is reached.
The copper element heats that water to 212°F, the boiling point at sea level. Vapor leaves the generator through an insulated steam line and travels to the steamhead, which can be up to 60 feet away when the line is properly insulated.
Steam enters the enclosure low and rises. A typical residential room reaches usable temperature in about 10 to 15 minutes, which is why most people start the generator before they get undressed.
From there the generator cycles. A temperature sensor in the room tells the control when to call for more steam and when to hold, so output rises and falls rather than running flat out the whole time.
Mr Steam residential generators carry a 60 minute automatic cut off, so the system shuts itself down whether or not you remember to. That's a safety feature, not a session recommendation, and 10 to 15 minutes is a normal session.
Then there's a step that happens after you've left the bathroom. Mr Steam's AutoFlush system drains the tank roughly two hours after a session, pushing sediment and leftover water out through an electronically activated valve so nothing sits stagnant.
Why the Room Feels Hotter Than the Number on the Control
A steam shower runs around 110 to 115°F, which sounds mild next to a sauna at 180°F. It doesn't feel mild, and there's a specific reason.
Your body cools itself by evaporating sweat off your skin, and at 100% humidity there's nowhere for that moisture to go. Evaporative cooling stalls, so your core temperature climbs faster than the air temperature suggests.
Push much past 120°F at full saturation and it stops being pleasant, which is why residential systems cap out where they do. We go deeper into the physics and the comparison in our guide to steam showers versus saunas.
What Makes a Shower Steam Ready
An existing shower can give you the footprint, but a standard shower is not automatically steam ready. Converting one is usually part of a real remodel rather than an afternoon project.
Here's what has to be true of the enclosure itself:
- A vapor barrier or waterproof membrane behind every surface, including the ceiling
- Non-porous surfaces such as tile, natural or engineered stone, or molded acrylic, and no wood
- A fully enclosed door and frame, with no open gap at the top or bottom
- A ceiling no higher than 8 feet, since going taller means upsizing the generator
- A slight ceiling slope in larger enclosures so condensation runs down the walls instead of dripping on your head
- No heating, cooling, or exhaust vents located inside the enclosure
- Double paned tempered safety glass for any window that's part of the steam room
That last group of items is where most failed installations come from. Skipping the membrane is how moisture ends up trapped behind tile, and the Tile Council of North America publishes the waterproofing guidelines most tile contractors work from.
Ventilation still matters, just not inside the box. An exhaust fan in the bathroom outside the enclosure handles drying the room between uses.
Where the Generator Goes and What It Needs
The generator never goes inside the steam room, and it never goes outdoors. It needs to stay dry, accessible, and above freezing.
Mr Steam recommends a closet, a vanity cabinet, a sealed bench, a basement, or a heated attic. It can sit up to 60 feet from the shower and even on a different floor, as long as the steam line is insulated.
Three connections make it run. A dedicated 208V or 240V circuit sized to the generator's output, a cold water supply line, and a drain for flushing the tank.
A few installation details matter more than they sound:
- Mount the unit upright and level, or the water level probes read wrong
- Leave 12 inches of clearance for future service, though the back can sit against a wall
- Pitch the steam line ¼ inch per foot, in either direction, so condensation drains out
- Never let the steam line dip down and back up, because that forms a trap and creates back pressure
- Don't use PEX, which isn't rated for the 212°F steam running through the line
- Insulate the line with 220 degree rated fiberglass to limit heat loss on long runs
Control wiring is the other planning item. Mr Steam controls ship with a 30 foot cable and a 60 foot version is available, or you can skip the cable question entirely with a wireless control.
That's what the ButlerFlex package solves, since its TempoFlex control talks to the generator over RF and works up to 90 feet away. It's the usual answer for retrofits where running new cable through finished walls isn't realistic.
Mr Steam ButlerFlex Control Package with TempoFlex Wireless Control
How Generator Sizing Actually Works
Generator capacity is measured in kilowatts, and the right number comes from the volume of your finished enclosure plus what it's lined with. Cubic feet alone won't get you there.
Glass, stone, and tile pull heat out of the room at different rates, so two showers with identical dimensions can need different generators. Marble and glass heavy enclosures need more capacity than the raw volume suggests.
Undersizing is the single most common mistake we see, and it's the one you can't fix later without replacing the unit. A generator that's too small never quite saturates the room, and one that's too large wastes energy and can overwhelm the space.
Rather than making people guess, we built a Mr Steam generator sizing calculator that takes your dimensions and surface materials and returns the right output. It takes about a minute.
What the Equipment Costs
Generator packages bundle the generator, a control, and a steamhead, which is how most residential systems are bought. Here are our current prices on three common sizes.
| Package | Output | Price from |
|---|---|---|
| Mr Steam MS 5 kW package with iTempo | 5 kW | $2,923 |
| Mr Steam MS 7.5 kW package with iTempo | 7.5 kW | $3,623 |
| Mr Steam MS 12 kW package with iTempo | 12 kW | $4,533 |
Those are equipment prices only. They don't include tile, the vapor membrane, the sloped ceiling, glass, or labor, and those swing enormously by market and by how much of the bathroom you're already redoing.
Mr Steam MS 12 kW Steam Shower Generator Package with iTempo Control
If you'd rather buy the pieces separately, we list steam generators on their own and control and steamhead packages as separate line items.
Not sure what size you need? Send us your enclosure dimensions and surface materials and we'll size it for you at no charge, or call and text us at 707-297-3991. We'd much rather do this before the tile goes up than after.
Frequently Asked Questions
How long does a steam shower take to heat up?
Roughly 10 to 15 minutes for a correctly sized residential system. Undersized generators take noticeably longer and may never fully saturate the room.
What's the point of a steam shower?
Heat therapy without leaving the house, in a space you already have. People use it for muscle relaxation after training, for comfort while congested, and because saturated heat is pleasant.
How much water does a steam shower use?
Mr Steam puts a typical 20 minute session at under two gallons, compared with 65 plus gallons for a bath. The running cost is mostly electricity, not water.
Does a steam shower need its own electrical circuit?
Yes. Residential generators run on a dedicated 208V or 240V circuit sized to the unit's output, which is work for a licensed electrician.
Can you convert an existing shower into a steam shower?
Often, but not by just adding a generator. The enclosure has to be made vapor tight, which usually means opening the walls, so the practical window is during a remodel.
Does a steam shower need an exhaust fan?
Not inside the enclosure, and vents should never be located in there. An exhaust fan in the bathroom outside the shower handles drying the space between uses.
What maintenance does the generator need?
Flushing the tank is the main thing, and AutoFlush handles it automatically after every session. Leave 12 inches of service clearance so a technician can reach the unit when it eventually needs attention.
Thinking about adding steam at home? We're an authorized Mr Steam dealer, and we'll size your generator correctly for your enclosure before you buy anything.
Browse our complete steam shower packages, or call and text us at 707-297-3991.
Technical specifications in this article come from Mr Steam's published technical documentation and residential generator specifications. Prices are our current listed prices and are subject to change.
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