Commercial Sauna Costs: What UK Gyms, Hotels and Spas Actually Pay

The short answer

Budget £15,000 to £60,000 for a commercial sauna installed in the UK, and £500 to £1,000 a month to run one hard. The cabin itself is rarely the problem. What moves the number by tens of thousands is the electrical supply: commercial heaters need 400V three-phase, and if your building hasn’t got it, a new supply from your network operator can cost more than the sauna.

The figures below come from UK supplier list prices, manufacturer specifications and installer quotes current in 2026. They’re ranges rather than estimates because two venues buying an identical cabin can pay £20,000 apart once groundwork, power and access are counted.

Capital cost, line by line

Most quotes bundle everything into one number, which makes them impossible to compare. Break it down like this and you can see where a supplier is cheap and where they’re hiding cost.

Line item	Typical UK cost	Notes
Sauna cabin or panel system (6–8 person)	£8,000–£30,000	The headline figure most suppliers quote
Commercial heater (12–18kW)	£1,500–£4,000	Plus a control unit, often £300–£800 extra
Sauna stones	£150–£400	An 18kW heater takes around 250kg
Electrical installation (three-phase already present)	£800–£2,500	Certified commercial electrician, BS 7671
New three-phase supply (if needed)	£3,000–£15,000+	DNO-dependent; can take 3–6 months
Ventilation (mechanical, sized to occupancy)	£500–£3,000	Often overlooked until building control ask
Groundwork / base (outdoor units)	£1,000–£5,000	Level, load-bearing, drained
Delivery and craning	£500–£3,000	Hiab hire for container and cabin units
Building regs and professional fees	£500–£2,500	Higher if planning permission is needed

Add those up and a realistic all-in figure for a venue that already has three-phase power is £15,000–£35,000. A venue that doesn’t, and needs an outdoor base and a crane, is looking at £35,000–£60,000 or more.

The three-phase question, and why it dominates the budget

This is the single biggest swing factor, so resolve it before you get quotes.

Commercial-output heaters are three-phase by necessity, not preference. HUUM’s specification for the HIVE 18 lists an 18kW output on a 3/N~400V supply with a 32A fuse and 5 × 6mm² cable. The same heater on single-phase 230V would pull roughly 78A — more than most buildings’ entire main fuse. Split across three phases it’s about 26A per phase.

So the first call you make isn’t to a sauna supplier. It’s to check your incoming supply:

• You have three-phase. Common in industrial units, leisure centres, larger hotels and anywhere with commercial catering or lifts. Your electrical cost is £800–£2,500 and you can get on with it.
• You don’t. A new supply is quoted by your Distribution Network Operator and depends almost entirely on how far away the nearest three-phase network is. Budget four figures minimum, five if the road needs digging, and three to six months.
• You can’t get it, or won’t pay for it. Two honest options: a wood-fired heater (removes the electrical load entirely, adds a flue, fuel, ash and staff time), or accept a smaller room on a large single-phase heater — roughly four to six people, which may not meet your throughput.

Note that a commercial installation isn’t covered by Approved Document P, which applies to dwellings. It falls under BS 7671 and the Electricity at Work Regulations 1989, so you need an electrician with genuine commercial experience — and the certification, because your insurer will ask for it.

What it costs to run

Electricity is the cost people underestimate, partly because heater ratings sound alarming and partly because heaters don’t draw their rated output continuously.

An 18kW heater runs near full draw during warm-up, then cycles thermostatically to hold temperature. Working it through for a full operating day:

Phase	Consumption	At 26–30p/kWh
Warm-up (45–60 min, near full draw)	15–18 kWh	£4–£5
Holding temperature (12 hours, 35–50% duty)	75–110 kWh	£20–£33
Full operating day	90–130 kWh	£23–£39

Those are calculated from the heater rating and a duty-cycle assumption, not metered readings — a well-insulated room at the lower end of its volume range will beat them, and a room with a door opening every ninety seconds will not. Business electricity has sat broadly in the 25–30p/kWh range through 2026, but commercial contracts vary far more than domestic ones, so use your own unit rate.

Beyond electricity, the recurring costs are modest but real: stones need replacing every one to two years under heavy use (£150–£400), heater elements every three to five years, timber treatment and bench cleaning, and an annual electrical inspection. Call it £1,500–£3,000 a year on top of energy.

Does it pay for itself?

Honestly, it depends on whether you’re selling sauna or selling memberships.

As a standalone revenue line, the maths is tight. At £10–£15 a session you need roughly three paying users a day just to cover £23–£39 of electricity, which sounds easy until you account for rent, staff and quiet Tuesday mornings. Standalone sauna venues live or die on utilisation, and utilisation is seasonal.

As an addition to an existing membership — a gym, a padel or racket club, a campsite, a hotel spa — it usually stacks up far better, because the footfall already exists and the sauna is doing retention work rather than needing to fill itself. A £25,000 install spread over five years is roughly £420 a month; if it reduces monthly churn by even a handful of members, it has paid for itself without selling a single session.

The version that rarely works is a large sauna bought to fix a footfall problem. If people aren’t coming, a sauna won’t make them.

Where venues waste money

• Buying a domestic cabin with a bigger heater. Commercial duty cycles destroy domestic benching and controls. This is the most expensive false economy in the category — you replace it in two years.
• Undersizing the heater for the room volume. The heater then runs permanently at full draw trying to hold temperature, burning elements and electricity. Every manufacturer publishes a minimum and maximum room volume; stay inside it.
• Leaving ventilation until building control ask. Retro-fitting mechanical ventilation into a finished sauna costs multiples of designing it in.
• Not pricing the crane. Container and finished-cabin units need a hiab and a clear route. Measure gateways and check for overhead cables before you order.
• Telling the insurer afterwards. Public liability cover frequently carries conditions on supervision, session-length signage and a cut-off timer. Find out before you specify the controls, not after.

Getting a quote worth comparing

Ask every supplier for the same nine line items in the table above, separately. Then ask three specific questions that separate serious commercial suppliers from resellers:

1. What heater output do you recommend for this room volume, and what’s the manufacturer’s rated range? If they can’t answer with a number, they haven’t specified a commercial sauna before.
2. What electrical supply does it need, and will you provide the BS 7671 certification?
3. What’s the warranty on the benching and the heater separately, under commercial use? Domestic warranties are often void in a commercial setting.

Frequently asked questions

How much does a commercial sauna cost in the UK?

Between roughly £15,000 and £60,000 installed. The cabin or panel system is £8,000–£30,000 for a six-to-eight person room, and the rest is heater, electrics, ventilation, groundwork, delivery and fees. The biggest single variable is whether your building already has a 400V three-phase supply — if it doesn’t, a new one can add £3,000–£15,000 and several months.

How much does a commercial sauna cost to run?

Roughly £23–£39 a day in electricity for an 18kW unit running a full operating day, based on 90–130kWh at 26–30p/kWh. Over a month that’s £500–£1,000 for a hard-working sauna, plus around £1,500–£3,000 a year for stones, elements, cleaning and inspection. A smaller 12kW room used part-time costs considerably less.

Do you need three-phase electricity for a commercial sauna?

For a commercial-output electric heater, yes. Outputs of 12kW and above are specified for 400V three-phase because the single-phase current draw would be impractical — an 18kW heater on 230V would need around 78A. If three-phase isn’t available and can’t be economically installed, the realistic alternatives are a wood-fired heater or a smaller room on a large single-phase unit, which limits you to about four to six people.

Is a commercial sauna cheaper to buy ready-made or built on site?

A modular panel system is usually the lowest headline cost for a regular indoor room with good access. A finished, delivered cabin often works out better value than it first appears because it removes the construction risk — no trades on site for weeks, no discovering what’s behind the wall. A fully bespoke fit-out is the most expensive and makes sense when the space is awkward, the building is listed, or the design matters commercially.

Next steps

Start with the supply check, because it determines everything else. Our guide to commercial saunas covers specification and compliance in more depth, and if the unit needs to move between sites, mobile saunas is the better starting point. For the domestic end of the market, see how much a sauna costs in the UK.

When you’re ready for real numbers, find a UK sauna builder who takes commercial commissions and ask for a site visit. A quote from someone who has seen your meter and your access route is worth more than any range on this page. You can also enquire about the Hot Box, a finished eight-person unit from our commercial partner Hot Blue (see our affiliate disclosure), or browse our other installation and planning guides.