What affects the cost of a sauna or steam room

The short answer

The cost of a sauna or steam room is driven less by its floor area than by what it is built from, what equipment it needs, what the site already provides and how hard the room will work.

• The room itself: size, layout, ceiling height, timber, glass and finishes.
• The equipment: heater or steam generator, controls and lighting.
• The building and services: structure, electrical supply, water, drainage, ventilation and plant space.
• The site and the use: access, indoor or outdoor, and home or commercial duty.

This guide does not give prices, because they depend on all of the above. It explains why each factor matters, so you can see where your project sits and decide where to spend.

Size and layout

A larger room needs more timber or tile, more lining and insulation, and usually a larger heater or generator. But layout often matters as much as area:

• Ceiling height. Taller rooms add volume to heat and, in a sauna, need taller benches or more tiers to keep bathers in the hot layer. In a steam room, a sloped, curved or domed ceiling is part of the design and adds framing and finishing work.
• Benches. Multi-tier benches, L-shaped or U-shaped layouts, lying-length benches and curved forms take more material and more workshop time than a single straight bench.
• Shape. Curves, angled walls, niches and integrated changing areas take more design and fabrication than a simple rectangle.
• Fit to the space. A room that has to fit an existing space, work around existing services or match surrounding architecture needs more measurement and coordination.

See planning a home sauna for how size relates to the number of people using the room.

Custom, kit or equipment only

The scope you ask for changes what is being priced.

A custom sauna or steam room suits a room that must fit the architecture or a particular space. Sauna kits suit a freestanding sauna where a standard size works. Equipment-only supply suits a project where a builder or bathroom designer is delivering the room; ask whether sizing support is part of it.

Timber species and grade

In a sauna, timber is one of the most visible cost choices. Clear, knot-free timber costs more than knotty grades, and it is essential for anything you sit or lean on. Walls and ceilings can use a knotty grade to manage budget without affecting comfort.

Species, availability and certification also affect cost, as do the profile and how the boards are detailed: concealed fixings, curved work, lift-out bench sections and lining run in a particular direction all take time. Our guides to choosing sauna timber and comparing cedar, aspen and hemlock cover the choices in detail.

Glazing and doors

Glass is a cost in itself and a cost multiplier.

• The glass. Glass doors, side panels, full glass fronts and external windows each need toughened safety glass, framing or fixings and hardware suited to heat and, in a steam room, constant moisture. Large frameless panels can add structural fixing work.
• The equipment. Glass loses heat faster than an insulated wall. Sauna heater manufacturers add notional room volume for each square metre of glass. One widely used heater range adds about 1.2 m³ per square metre, which can move the selection up one or more heater sizes. Steam generator manufacturers make similar allowances.
• Steam doors. Manufacturers differ on whether the door should be gasketed and sealed or have a deliberate gap underneath, and that choice is tied to the generator system.

Heater or steam generator

The heater or generator is chosen for the room, and its size follows the room’s volume and construction, not just its floor area. The type also matters:

• Sauna heaters range from compact wall-mounted units to floor-standing heaters with large stone loads. Heaters controlled by a separate control unit need that unit as well. Heat-storage designs that stay warm on standby have a different energy profile.
• Steam generators are sized from the room volume and, just as importantly, the wall and ceiling build-up and the ventilation approach. Stone and masonry rooms need considerably more output than tile on insulated board. See sizing a steam generator.
• Commercial-duty equipment is a different class of product, with higher outputs, serviceability features and different warranty terms.

A larger output can also mean a larger electrical supply, which is one reason equipment selection comes early.

Controls

Controls range from a simple control panel to Wi-Fi control, scheduling, multi-room management and building-management connections. Remote and app start bring additional safety requirements, such as a door switch, set by the manufacturer. Commercial rooms may add door sensors, emergency call points linked to a staffed desk, timers and integration with the building’s systems. Each of these adds equipment, cabling and commissioning time.

Lighting

Sauna lighting must suit the temperature at its position, so fittings are rated for heat and are usually kept low in the room, such as under benches. Steam-room lighting must suit saturated air and be sealed into the vapour-control layer. Feature lighting, concealed linear lighting and colour control add fittings, drivers, cabling and coordination with the electrician.

Steam rooms: finishes, vapour control and the ceiling

A steam room is not a shower with a steam generator added. Several of its costs are invisible once the tiles are on:

• Vapour control and waterproofing. A continuous, low-permeance vapour-control system across walls, ceiling and floor, with every penetration sealed. Systems rated for continuous commercial use can be a heavier grade.
• The ceiling. A sloped, curved or domed ceiling to shed condensate, framed in and lined with the same system.
• Benches. Formed, waterproofed and tiled, sometimes heated.
• Finishes. Tile choice, heat-rated adhesives and epoxy grout, and the labour of tiling slopes, curves and benches. Natural stone needs caution: several manufacturers advise against porous stone in steam rooms, and heavy, dense finishes need a larger generator.

Our guide to steam room design and construction explains why each of these matters.

Plant room and services

The services a room needs are often a larger share of the work than people expect.

• Electrical capacity. Heaters and steam generators are large fixed loads. Some smaller heaters come in single-phase versions, depending on the model, while larger heaters commonly need three-phase supply. If the site supply or switchboard cannot carry the new load, upgrade work may be needed. A licensed electrician assesses this from the selected equipment’s data.
• Plumbing and drainage. Steam rooms need a water supply to the generator, a drain in the room, and a drain in the plant space for the generator’s hot discharge. A softener may be needed where water is hard. Saunas may have a floor waste.
• Ventilation. Saunas need inlet and exhaust arrangements to the heater manufacturer’s layout. Commercial steam rooms often need mechanical ventilation designed by a mechanical engineer.
• Plant space. A steam generator sits outside the room in a dry, ventilated, accessible space within the manufacturer’s pipe-length limit. Creating that space, if it does not already exist, is part of the project.

See services coordination for saunas and steam rooms for what each trade needs.

Access and site conditions

• Access. Narrow stairs, lifts, upper floors, long carries and restricted parking all affect delivery and installation time. Large prefabricated sections or kits need a clear delivery route.
• Structure. Large floor-standing heaters with heavy stone loads, tiled masonry benches and big glass panels add weight. Suspended floors may need an engineer’s review and reinforcement.
• Existing conditions. Out-of-square walls, uneven floors, existing services to move and the need to protect finished areas in an occupied home all add work.
• Location. Travel to regional sites adds time.

Indoor or outdoor

An indoor room relies on the building for weather protection. An outdoor sauna has to provide its own:

• a level, well-drained base or slab
• roofing and weatherproofing suited to Queensland sun, rain and humidity
• a power supply run from the switchboard, sometimes a long distance
• and, depending on the structure and site, council or building approval.

Our guide to outdoor sauna kits in Queensland covers siting, the base and approvals.

Commercial duty

A sauna or steam room in a hotel, gym, day spa or apartment building works far harder than one at home, and the specification changes to suit:

• commercial-rated heaters and generators, often with higher outputs and serviceability features
• more robust benches, replaceable slats and hard-wearing finishes
• continuous-use waterproofing systems and mechanical ventilation for steam
• supervision and safety features such as door sensors and emergency call points
• plant-room access, water treatment and professional servicing.

Manufacturers’ warranties for commercial and institutional use are typically shorter than for home use, which makes a service plan part of the budget from the start. See commercial saunas and steam rooms.

Design and coordination

Design work is a real part of the scope. A simple room in an open space needs less of it than a room integrated into a new building, where the specialist works with the architect, builder, engineers, trades and certifier.

Timing matters too. When a sauna or steam room is planned before framing, ceiling heights, reinforcement, drainage, plant space and electrical supply can be allowed for at little extra effort. When it is added late, some of those items may have to be reworked. Early involvement is usually the most economical path. See when to involve a specialist and our page for architects and builders.

Running and maintenance

No figures are given here, because running costs depend on your tariff, use and room. What drives them is predictable:

• Output and hours. Energy use follows the heater or generator output and how long it runs. Manufacturers commonly quote about an hour for a correctly sized sauna heater to bring an insulated room to temperature, and that heat-up is part of every session.
• The room. Good insulation, a sensible ceiling height and limited glass reduce the energy needed.
• Standby. Heat-storage heaters kept warm on standby use energy continuously. One manufacturer quotes 4–6 kWh a day for its model.
• Consumables. Sauna stones are checked and re-stacked or replaced periodically, far more often in commercial use. Steam generators need descaling by operating hours and water hardness, and softener supplies where fitted.
• Servicing. Commercial rooms carry scheduled professional servicing; one steam generator manufacturer specifies at least twice a year for institutional use.

Estimating energy use yourself

You can make a reasonable estimate of a sauna’s energy use without a price list. Harvia explains that an electric heater runs at full capacity for roughly the first 30 to 40 minutes, then at about half its maximum power while the room is held at temperature. Its worked example, for a 6 kW heater in an insulated sauna for three or four people:

• first hour, mostly heating up: about 4–5 kWh
• second hour, holding temperature: about 3–4 kWh
• about 7–9 kWh for two hours

Multiply your own figure by your electricity tariff per kWh, and by the number of sessions. A larger heater, a colder or glassier room, or longer sessions will use more; a well-insulated room and a heater sized to it will use less. Your heater’s thermostat, not its rated output, decides how much power it actually draws once the room is warm.

What a specialist quote usually covers

Every supplier and contract divides the work differently. As a general guide only:

When comparing quotes, line them up against a list like this. A lower number sometimes reflects a narrower scope rather than a lower cost.

How to get an accurate quote

The more of this you can send, the closer a quote will be to the final scope.

1. Drawings. Floor plan, sections or elevations, ceiling height, and the room’s position in the building. Sketches with dimensions are a good start.
2. Photos. The space, the access route, the switchboard and any proposed plant location.
3. Use. Home or commercial; how many people at once; for commercial rooms, expected hours a day.
4. Room type. Sauna (traditional, infrared or hybrid) or steam room, and any must-haves.
5. The look. Timber, tile or stone preferences, glass, lighting and reference images.
6. Indoor or outdoor. For outdoor rooms, the site, base and distance from the switchboard.
7. Services. Single-phase or three-phase supply if known, water and drainage nearby, and ventilation options.
8. Scope. Design only, equipment only, kit, or design, supply and installation.
9. Timing. Your programme, the current design stage, and who the architect and builder are.
10. Priorities. What matters most to you, and where you are prepared to compromise.