Adding a steam shower to your bathroom is one of the most rewarding home upgrades you can make — but unlike swapping out a showerhead, it involves plumbing, electrical, waterproofing, and structural considerations that need to be planned before a single tile goes up. Get these right during the design phase and the installation is smooth. Miss one and you are retiling a wall or rerouting pipe after the fact.
This guide covers every requirement your contractor will need to know before installing a steam shower with a Mr. Steam, ThermaSol, or Amerec generator.
1. The Enclosure Must Be Fully Sealed
Steam requires a completely sealed enclosure. Unlike a regular shower, steam will find every gap and escape — driving moisture into walls, ceilings, and framing. Before your generator is even sized, your enclosure needs to meet these requirements:
- A door that seals. Steam shower doors must close tightly with minimal gaps. Frameless glass doors with proper seals work well. Curtains are not suitable.
- Waterproof walls and ceiling. Every surface inside the enclosure must be waterproofed — tile, natural stone, acrylic panels, or glass. Standard drywall behind tile is not acceptable; cement board or a dedicated waterproof membrane is required.
- A sloped ceiling. The ceiling inside the steam shower must slope at least 2 inches per foot from the highest point toward the walls. Without a slope, condensation pools and drips cold water on bathers. This is one of the most commonly missed requirements.
- Minimum 3 ft × 3 ft enclosure. This is the practical minimum for a single-person steam shower. Most comfortable single-person enclosures are 4 ft × 4 ft or larger.
Ceiling height: All three brands recommend a maximum ceiling height of 8 ft for best performance. Higher ceilings are possible but require a larger generator — steam rises and the bather-level environment becomes less efficient. See our Steam Shower Sizing Calculator for ceiling height adjustments by brand.
2. The Generator Location
The steam generator does not go inside the shower. It installs nearby in a dry, well-ventilated, temperature-controlled space — a cabinet, closet, under a sealed bench, or in a finished mechanical room. Here is what each brand requires:
- Mr. Steam: Up to 60 feet from the steam room. Requires zero clearance — can be placed flush against a wall. Must be in a dry, heated location. MS Series dimensions: 14.5" × 14.75" × 6.75". Super Series: 17" × 18.5" × 7.9". MX Series: 27.625" × 20.75" × 7.875".
- ThermaSol: Up to 50 feet from the steam room. Must be in a finished, climate-controlled space with 6 inches of clearance on all sides.
- Amerec: Mount level, in a dry well-ventilated area not exposed to freezing temperatures. Can be mounted on its base or hung on a wall. All AK4.5–AK14 generators share the same shipping box: 22" × 20" × 10.5".
Plan your generator location before tiling. The steam line runs from the generator to the steamhead inside the shower. If this line is longer than 20 feet, it must be insulated to prevent condensation buildup. Do not create traps in the steam line — slope it to avoid condensation.
3. Plumbing Requirements
A steam generator requires three separate plumbing connections. These need to be roughed in before walls are closed:
- Cold water supply — 3/8" copper line. The generator draws cold water to produce steam. Install a shutoff valve on this line. Do not use a saddle valve — a proper tee fitting is required. The water inlet on Mr. Steam and Amerec generators is 3/8" NPT.
- Steam line — 1/2" copper line. Runs from the generator to the steamhead inside the shower. Slope the pipe to avoid condensation traps. Insulate any runs over 20 feet. Mr. Steam's 2025 generators feature an updated 3/4" steam line for improved performance — confirm with your specific model.
- Drain line — 3/4" copper line. The generator drains after each session. Slope to gravity flow drain. Do not terminate the drain line inside the steam room. The drain outlet on both Mr. Steam and Amerec generators is 3/4" NPT.
- Pressure relief valve — 3/4" copper line. Required on all generators. Terminate in accordance with local and national plumbing codes.
4. Electrical Requirements
Every steam generator requires a dedicated electrical circuit. This is non-negotiable — sharing a circuit with other devices will trip breakers and may damage the generator. All wiring must be installed by a licensed electrician in accordance with local and national electrical codes.
The specific amperage and wire gauge required depends on your generator model and voltage. As a general reference from the 2025 Mr. Steam spec chart:
| Model | kW | Amps (240V/1PH) | Wire Size (AWG) |
|---|---|---|---|
| MS90R | 5 | 21 | 10 |
| MS150R | 6 | 25 | 8 |
| MS225R | 7.5 | 32 | 8 |
| MS400R | 9 | 38 | 8 |
| MSSUPER1R | 10 | 42 | 8 |
| MSSUPER2R | 12 | 50 | 6 |
| MSSUPER3R | 15 | 63 | 4 |
| MX4R | 20 | 84 | 3 |
| MX5R | 24 | 100 | 1 |
| MX6R | 30 | 125 | 2/0 |
Always verify with your specific model's installation manual. Wire sizing is based on minimum 90°C rated THHN copper conductors. Refer to the National Electrical Code for other conductor types. Amerec and ThermaSol generators have their own amperage and breaker requirements — check the spec sheet for your exact model.
5. The Steamhead Location
The steamhead is the outlet inside the shower where steam enters the enclosure. Its placement directly affects how comfortable the steam experience is:
- Height: Mount 18 inches above the floor, or 6 inches above the rim of a bathtub. This is the Amerec specification and is consistent with best practice across all brands.
- Position: As far from the seating area as possible, on the wall opposite where the bather sits. Steam should travel across the enclosure before reaching the bather.
- Quantity: One steamhead is standard for most residential enclosures. Amerec requires two steamheads for the AK14 generator. Mr. Steam's MX4, MX5, and MX6 generators require two Linear SteamHeads if that style is used.
6. The Control Location
Steam shower controls can be mounted inside or outside the enclosure. If mounted outside, a Temperature Probe must be installed inside the shower so the control can accurately read the enclosure temperature. All Mr. Steam, ThermaSol, and Amerec controls are waterproof to IP67 standards and rated for inside the steam room. The control wire runs from the control to the generator — plan this route before walls close.
The TempoFlex is the only exception — as an RF wireless control it requires no control wire to the generator at all, making it ideal for retrofits where running new cable is impractical.
7. Ventilation
A steam shower should not have an active exhaust fan running during a steam session — it will pull the steam out. However, ventilation after the session is essential to dry out the enclosure and prevent mold. A timer-controlled exhaust fan that activates after the steam session ends is the recommended approach. The generator room or closet where the unit is installed also requires adequate ventilation — do not install in a sealed, unventilated space.
8. Water Quality & Maintenance Planning
Hard water is the most common cause of generator failure over time. Mineral scale builds up on heating elements and reduces efficiency. Plan for this before installation:
- For Mr. Steam generators (MS90R–MSSUPER3R), the AutoFlush system automatically flushes the generator two hours after every session and introduces fresh water before each use — install it at the same time as the generator.
- For Amerec generators, the ADK Auto Drain kit performs the same function. It is included in both the Glacier and Columbia control packages.
- A drip pan under the generator is required and comes included with most Mr. Steam and Amerec package options.
Read our full guide: Hard Water & Steam Generators: How to Protect Your Investment
Pre-Installation Checklist
Before your contractor begins, confirm all of the following:
- Enclosure is fully sealed — waterproof walls, ceiling, and door
- Ceiling slopes at least 2 inches per foot
- Generator location identified — dry, ventilated, temperature-controlled
- Steam line route planned — insulated if over 20 ft, no traps
- Cold water supply roughed in — 3/8" copper, proper shutoff valve
- Drain line roughed in — 3/4" copper, sloped to gravity drain
- Dedicated electrical circuit sized to your generator model
- Steamhead location marked — 18" above floor, opposite seating
- Control wire route planned
- AutoFlush or auto-drain included in the order
Frequently Asked Questions
Can I convert an existing shower into a steam shower?
Yes — if the existing enclosure can be fully sealed and waterproofed. The biggest variables are whether the ceiling can be sloped, whether a nearby generator location exists, and whether a dedicated electrical circuit can be added. Many retrofits are straightforward; some require more significant work depending on the bathroom layout.
Does the generator need to be in the same room as the shower?
No — Mr. Steam generators can be installed up to 60 feet away, ThermaSol up to 50 feet. A nearby cabinet, closet, or mechanical room works perfectly.
Do I need a permit?
In most jurisdictions, yes — electrical work and plumbing modifications require permits. Your licensed contractor will handle this. Always install to local code.
How long does installation take?
For a new build where rough-in happens during framing, a steam shower adds minimal time to the project. For a retrofit in an existing bathroom, plan for 1–3 days depending on complexity — more if walls need to be opened for plumbing or electrical.
Why Order from TheSteamStore.com?
- Expert Sizing Help: Not sure which generator is right for your enclosure? Use our Steam Shower Sizing Calculator or contact us directly.
- All Three Brands: We carry Mr. Steam, ThermaSol, and Amerec — compare all three in one place.
- Free Shipping: All orders over $199 ship free within the contiguous United States.
Ready to get started? Browse our full selection of Mr. Steam, ThermaSol, and Amerec generators at TheSteamStore.com.