Steam Shower, Sauna & Commercial Steam Room: Contractor Guide

Steam shower installations are one of the most profitable and repeatable add-ons a plumbing contractor can offer. But the rough-in details need to be right before tile goes up — and understanding the difference between steam showers, home saunas, and commercial steam rooms helps you spec the right system, quote the right job, and avoid callbacks. This guide covers the facts a contractor needs across all three product types.

At PlumbersCrib.com, we are an authorized dealer of Mr. Steam, ThermaSol, and Amerec — three of the most specified steam brands in residential and commercial construction — and we have been supplying contractors and wholesale buyers across the US for over 20 years.

How steam showers and saunas actually work

Understanding the physical difference between these two environments is the starting point for every spec conversation with a client.

A steam shower uses an electric steam generator to heat water to boiling point and pump steam into a sealed enclosure. The operating environment is 110–120°F with humidity near 100%. The generator is installed outside the shower in a nearby cabinet, closet, or mechanical room, connected to a cold water supply line and a dedicated 240V electrical circuit. At that humidity level, moist heat transfers to the body much more efficiently than dry air at the same temperature — which is why the benefits are meaningful at a relatively moderate temperature.

A traditional sauna uses an electric or wood-burning heater to heat a wood-lined room to 150–195°F with humidity typically between 5% and 20%. The low humidity allows the body to tolerate much higher temperatures — dry air does not conduct heat to the skin as rapidly as moist air. Löyly — pouring water over heated rocks — temporarily spikes humidity for a brief, intensified heat sensation before the room returns to low humidity.

Both environments raise core body temperature, trigger vasodilation, and produce sweat. The differences lie in how they do it, which affects the installation requirements, the enclosure spec, and which clients each option suits.

Steam shower vs. sauna: side by side

For a complete pre-installation checklist covering enclosure spec, plumbing rough-in, electrical requirements, steamhead placement, and control wiring, see our steam shower installation requirements guide.

What the research says about health benefits

Understanding the documented benefits helps during the client conversation — especially when justifying the cost of a premium system. Here is what the evidence actually supports.

Cardiovascular health. A landmark 21-year study published in JAMA Internal Medicine (2015) followed over 2,300 middle-aged Finnish men and found that those who used the sauna 4–7 times per week were 63% less likely to experience sudden cardiac death compared to once-a-week users. Heart rate during both steam and sauna sessions increases comparably to mild aerobic exercise, driven by vasodilation — the widening of blood vessels in response to heat — which lowers vascular resistance and improves blood pressure.

Respiratory relief. This is where steam showers have a specific, documented advantage over dry saunas. Inhaling humidified warm air at near-100% humidity reduces airway resistance and loosens mucus in the nasal passages, throat, and lungs. Research published in the European Respiratory Journal found that steam inhalation improved breathing comfort in patients with chronic sinusitis. Clients with asthma often find steam showers easier to tolerate than dry saunas for this reason.

Muscle recovery. A study in the Journal of Athletic Training found that moist heat was significantly more effective than dry heat for reducing delayed-onset muscle soreness (DOMS). Heat increases local blood flow, relaxes muscle fibers, and accelerates clearance of metabolic waste products including lactic acid — making a post-workout steam shower one of the most practical recovery tools available.

Skin health. Steam opens pores and promotes sweating, which clears sebum buildup and surface impurities. The near-100% humidity environment directly hydrates the skin — water vapor is absorbed through the skin surface — in a way that dry heat cannot replicate.

Stress and sleep. Heat exposure reduces cortisol — the body's primary stress hormone — and increases beta-endorphin production. A meta-analysis in Sleep Medicine Reviews found that passive body heating before sleep significantly improved slow-wave deep sleep quality in both healthy individuals and those with insomnia.

Immune support. Research published in the Annals of Medicine found that frequent sauna users experienced significantly fewer upper respiratory infections. The elevated core temperature during a heat session activates heat-shock protein production and increases white blood cell activity.

What a steam shower installation actually requires

Four things must be in place before a steam generator goes in. Every one of them needs to be confirmed before walls close.

• A fully enclosed shower — the enclosure must be sealed with a door and no large gaps. Minimum practical size is 3×3 ft; 4×4 ft is more comfortable for most clients. Waterproof substrate — cement board or a dedicated waterproof membrane — is required on all surfaces. Ceiling must slope a minimum of 2 inches per foot to drain condensation. Miss the ceiling slope and you get callbacks from clients complaining about cold water dripping on them mid-session
• A steam generator — sized to the cubic volume of the enclosure (length × width × height). Mr. Steam and Amerec apply a material multiplier for natural stone: multiply the base cubic footage by 1.75 for marble, granite, travertine, or slate before selecting a model. ThermaSol sizes by cubic footage only — wall material does not affect the sizing formula. For a complete sizing walkthrough by brand, see our steam sizing calculator
• Plumbing rough-in — three connections required: 3/8" cold water supply with a shutoff valve (no saddle valves — a proper tee fitting is required), 1/2" copper steam line sloped continuously with no traps and insulated on runs over 20 ft, and a 3/4" drain line sloped to a gravity drain. Use only copper or brass for steam lines — PEX and PVC are not acceptable
• A dedicated 240V electrical circuit — no GFI required. All wiring by a licensed electrician per NEC and local codes. A separate circuit breaker between the power supply and the generator is required, within sight of the unit or lockable in the open position. Mr. Steam generators can be placed up to 60 feet from the steamhead; ThermaSol up to 50 feet

For the full pre-installation checklist including control wire routing, steamhead placement specs, and ventilation requirements, see our steam shower installation requirements guide.

The brands we carry

PlumbersCrib.com carries three of the most specified steam brands in the trade. Each has a distinct approach and reputation worth knowing when you are advising a client.

Mr. Steam

Mr. Steam has been manufacturing residential and commercial steam systems in the United States for over 50 years, making it one of the most established and widely specified names in the category. The brand is built around reliability and breadth — covering everything from entry-level residential generators to large commercial installations, with a full range of controls, steamheads, and accessories engineered to work together. Mr. Steam is particularly well regarded in the trade for its AutoFlush technology — an automatic drain and flush system that activates two hours after every session, which is the most effective way to prevent mineral scale buildup and extend generator life. Its smart control ecosystem integrates with Amazon Alexa and supports Wi-Fi connectivity. For contractors who want a proven, full-featured system with the widest range of configurations and the most mature support network, Mr. Steam is consistently the most-specified brand in residential steam. Browse Mr. Steam.

ThermaSol

ThermaSol has been pioneering steam and shower technology since 1958, making it the oldest steam brand in North America. The company's focus has always been on engineering-led innovation — developing proprietary technologies rather than iterating on existing designs. ThermaSol holds multiple patents on core steam generation and control technologies, and its products are manufactured in the USA and backed by the industry's only no-questions-asked lifetime warranty. In 2024, ThermaSol joined the Harvia family of wellness brands — Harvia, founded in Finland in 1950, is the world's leading sauna and spa company operating in over 80 countries. That partnership deepens ThermaSol's reach into saunas, cold plunges, and hot soaks alongside its steam line. ThermaSol is the brand of choice for high-end residential projects and hospitality installations where performance and design integration are equally important. Its control systems integrate steam, water, lighting, audio, and streaming media into a single touchscreen interface. Browse ThermaSol.

Amerec

Amerec has built its reputation over decades as the contractor's preferred steam generator — the brand most commonly specified by plumbing and HVAC professionals for both residential and commercial installations. Amerec's approach is defined by practical engineering: consistent steam quality, durable construction, straightforward installation, and long-term serviceability in the field. The brand is particularly strong in commercial applications — health clubs, hotels, spas, and gyms — where generators need to perform reliably under heavy daily use year after year. Amerec generators are ETL listed for both the USA and Canada, use stainless steel tanks and removable heating elements throughout, and are designed to be serviced without specialized tools. All AK4.5 through AK14 units ship in the same box dimensions — 22" × 20" × 10.5" at 35 lbs — a practical advantage for tight installation spaces. The K2 control supports both Google Home and Amazon Alexa — the only residential steam control currently available with both voice assistant integrations. Browse Amerec.

Hard water and long-term maintenance

Mineral scale buildup — caused by calcium and magnesium deposits from hard water — is the leading cause of steam generator failure in the field. Spec the auto-drain at rough-in on every job. It is far easier to install during rough-in than after tile is up.

Mr. Steam's AutoFlush valve drains and flushes the generator two hours after every steam session automatically — no manual intervention required. ThermaSol's PRO Series III includes the PowerFlush automated cleaning system built into the generator. Amerec's ADK Auto Drain is included in both the Glacier and Columbia control packages — spec it on every AK job. For areas with exceptionally hard water, a point-of-use water softener upstream of the generator provides an additional layer of protection.

For a complete hard water guide including what happens when scale builds up and how to advise clients in hard water areas, see our steam shower benefits and maintenance guide.

Commercial steam rooms: specifying for hotels, spas, and clubs

Commercial steam room jobs differ from residential in several important ways worth knowing before you quote.

• Generator capacity — commercial rooms require larger units built for continuous daily use. ThermaSol's PowerPak Series III covers commercial applications at 18kW and 24kW, available in 208–240V and 480V three-phase configurations. Amerec AK Series units can be ganged together to cover rooms up to 1,500 cubic feet — only one control is needed regardless of how many generators are ganged
• Multi-room systems — ThermaSol's Day Spa Multi Room Steam System serves 2 to 4 separate steam rooms from a single generator at 10–20kW, purpose-built for spas and clubs where multiple simultaneous rooms are required
• Materials and serviceability — commercial generators use stainless steel tanks and removable heating elements. On Amerec units, heating elements are field-removable without specialized tools — a practical advantage on commercial service calls
• ADA compliance — bench height, door clearance, control placement, and floor slope all require specific design consideration. Confirm ADA requirements with the architect or GC before finalizing the spec
• Ventilation and drainage — commercial steam rooms require dedicated HVAC design and floor drain systems sized for continuous steam output. Do not use a standard residential exhaust fan — a timer-controlled fan activating after the session ends is the correct approach
• Three-phase power — most commercial installations will have three-phase power available. ThermaSol PowerPak and Amerec commercial units are available in both 208–240V and 480V three-phase configurations — confirm with the electrician before ordering

Browse our full commercial steam generator collection or contact us directly for help specifying the right system for your project.

Frequently asked questions

Can I add a steam generator to a client's existing shower?
Yes, provided the shower is fully enclosed with a minimum 3×3 ft floor area, a watertight door, and a dedicated 240V circuit can be run. The generator does not go in the bathroom — it installs in a nearby closet, cabinet, or mechanical room up to 50–60 feet away depending on the brand. Use our steam sizing calculator to identify the right model, or call us and we will size it for you.

Does wall material affect generator sizing?
Yes for Mr. Steam and Amerec — both use a 1.75 multiplier for natural stone (marble, granite, travertine, slate) applied to the base cubic footage before model selection. ThermaSol's sizing formula is based on cubic footage only and does not require a material adjustment regardless of wall type.

Is a GFI breaker required for a steam generator circuit?
No — steam generators require a dedicated 240V circuit without GFI protection. A standard circuit breaker between the power supply and the generator is required, within sight of the unit or lockable in the open position. All wiring per NEC and local codes by a licensed electrician.

What pipe material is required for the steam line?
Copper or brass only. PEX and PVC are not acceptable for steam lines. Use 1/2" copper, slope continuously to avoid condensation traps, and insulate all runs over 20 feet. Do not create any low spots or horizontal runs that will trap condensate.

Should I run an exhaust fan during a steam session?
No — an active exhaust fan during a steam session pulls steam out of the enclosure and defeats the purpose of the system. A timer-controlled exhaust fan that activates after the session ends is the correct approach. The generator room also requires adequate ventilation per manufacturer specs.

Do I need a permit for a steam shower installation?
In most jurisdictions, yes — an electrical permit for the 240V circuit and a plumbing permit for the water supply and drain connections are both typically required. Your electrician and plumber will handle the permit process. Always confirm with the local building department before starting.

Why order from PlumbersCrib.com?

• Authorized dealer — we are an authorized dealer of Mr. Steam, ThermaSol, and Amerec with full manufacturer warranty coverage
• Over 20 years serving contractors — residential and commercial clients across the US
• Free shipping — on all orders over $199 within the contiguous United States
• Technical support — call us at 877-881-5501 Monday through Friday, or contact us online — we know the electrical and plumbing requirements for every generator we carry

Ready to spec your next steam job?

Browse by what you need:

• Residential steam generators — Mr. Steam, ThermaSol, and Amerec
• Commercial steam generators — high-capacity units for spas, clubs, and hotels
• Complete wellness packages — generator, control, rainhead, and steamhead bundled
• Steam accessories — AutoFlush, drip pans, steamheads, and controls

Questions about sizing, electrical specs, or which brand is right for your project? Contact our team or call 877-881-5501 — we are here to help you spec it right the first time.