Adding a social sauna or bathhouse to your hotel, leisure club or spa: a UK feasibility guide

Britain has discovered the sauna, and not the quiet, solitary version tucked into a spa’s thermal suite. The sauna people are queuing for is communal, social, timed by the session, paired with a cold plunge, and increasingly described as an alternative to the pub. It started on beaches and in converted horse boxes. It is now a permanent fixture in cities, with multi-site operators, membership schemes and a national trade body publishing operator guidance.

For hotels, leisure clubs, health clubs and spas, that shift raises a practical question: can an existing venue add a social sauna or bathhouse offer, and does the case stack up? This guide is written for operators asking exactly that. It covers what has changed, the formats that are working, how the space differs from a conventional thermal suite, the planning and licensing requirements for a permanent commercial sauna in the UK, how the commercial model works, and the risks.

Two notes on how to read it. This is feasibility guidance from a design consultancy, and every figure comes from a published source, listed at the end. And planning and licensing vary by location, so every project needs local verification before commitment. If you are new to thermal facilities generally, our guide to the best types of saunas for spas covers the cabin types themselves. This page is about the business of running them socially.

What has changed: from silent spa to social sauna

The scale of the shift is measurable. According to the British Sauna Society, the number of public sauna sites in the UK rose from 45 in January 2023 to 147 in January 2025, a threefold increase in two years. Wild and pop-up saunas reached 213 by May 2025, double the previous year’s count. The Society’s UK Sauna Map, which uses a broader definition that includes saunas within the wider spa and wellness market, now lists more than 600 publicly accessible saunas.

London illustrates the pace. The capital now has more than 25 public sauna venues. Community Sauna Baths, a not-for-profit, grew to six sites by autumn 2025, each pairing communal cabins with cold plunges. Arc in Canary Wharf opened as the UK’s largest sauna and hosted a 350-attendee Sauna Summit in May 2025. In January 2026 the British Sauna Society published formal guidance for people setting up as sauna operators, the clearest possible signal that a hobbyist movement has professionalised.

The product is different from spa, and operators need to see that clearly before adding it. Social sauna sessions are timed, typically 60 to 90 minutes. They are communal, with strangers sharing a cabin. They are affordable, with community sessions priced well under a spa day. And they are social venues in their own right, described in coverage as alcohol-free places to meet people rather than places to be left alone. Research published in 2026 by the University of Greenwich, drawing on studies involving 1,907 UK sauna users, found that shared ritual and a sense of sauna identity were associated with social connection and improved self-reported wellbeing. The appeal is the company as much as the heat.

There is a competitive edge to this for established operators. IBISWorld’s analysis of the UK sauna sector notes that public outdoor saunas, often priced around £20, are now drawing custom away from commercial spas charging £100 to £200 for a day. An operator with an existing spa or leisure club is not just eyeing a new revenue line. They are deciding whether to compete with a format that is already competing with them.

The formats that are working

The successful venues share a recognisable template, visible in their own published descriptions. Community Sauna Baths’ Walthamstow site opened with three communal saunas, cold plunge pools, hot and cold showers, changing rooms and a shared relaxation space, with a community garden planned. Its Hackney Wick flagship arranges several differently shaped wooden cabins around a communal garden with cold plunges in repurposed whisky barrels. Cold contrast is standard rather than optional: almost every listed public sauna pairs heat with a plunge or cold shower.

Programming is treated as product. The national sauna directories categorise venues by what they run: guided sessions, Aufguss (the towel-waving heat ritual), single-gender sessions, social prescribing sessions, full moon events, story and art events, private group bookings. The cabin is the venue. The session is what people buy.

For an existing operator, there are three broad ways in.

The first is the lowest-risk entry and the one most venues with a garden, terrace or car park corner can consider. The third is the most ambitious and the most differentiated.

Space and design: how a social sauna differs from a spa thermal suite

This is where most projects go wrong, and it is a design question rather than an equipment one.

Rest and cooling capacity must exceed sauna capacity.

Design for Leisure’s contribution to the Global Wellness Institute’s hydrothermal development guide sets out the ratio: for every 15 minutes a guest spends in the heat, they will spend at least 20 and more likely 30 minutes cooling and resting before going back in. The cooling experience itself is short and sharp, so the space that matters is where people wait between rounds. The same source is blunt about the consequence: if guests cannot find a place to relax, they may not return, and for a venue built on repeat business, insufficient relaxation space can be a fatal flaw. Hot, cold and rest need to sit together as a circuit, in close proximity.

Outdoor space is disproportionately valuable.

The same guidance notes that outdoor areas are a prime attraction, especially in urban settings where guests may have little access to open space, and are relatively low-cost to maintain. A cool walk in fresh air after a hot sauna is a large part of the experience. This is why the successful venues are built around gardens rather than corridors.

The sizing figures are published.

Commercial sauna cabins are sized from the bench: roughly 600mm of bench per seated bather, ceiling heights of 2.1 to around 2.4 metres, and eight-person-plus commercial cabins from about 6 square metres upward. Changing needs a minimum of 1 square metre per guest at peak, with accessible provision to the Approved Document M minimum of 2200mm by 2000mm for a self-contained accessible changing or shower room. Our spa room dimensions and floor plans reference sets these out in full with their sources.

The session model makes sizing easier, not harder.

Because sessions are timed and bookable, peak occupancy is known in advance rather than guessed. If three eight-person cabins run a session together, the changing and cooling spaces need to handle 24 arrivals and 24 departures at fixed times, which is a far more predictable design brief than a drop-in spa. It also means the circuit can be sized precisely to the session, with no expensive slack.

The example above shows a bolt-on outdoor circuit of roughly 200 square metres: three eight-person cabins, cold showers, a plunge, and a cooling garden with rest seating, supported by changing and a relaxation room on the indoor side connecting to the host venue. The numbered loop is the point: sauna, cold shower, plunge, rest, repeat, all within a few metres of each other. It is illustrative, not a project drawing, and every dimension would be verified at design stage.

Planning permission, building regulations and licensing

This is the section with the least reliable information online, because almost everything published about sauna regulation concerns mobile trailers on beaches. A permanent commercial sauna at an existing venue is a different proposition on all three counts.

Planning.

A fixed commercial sauna may require planning permission, particularly where it involves a change of use of the land or building, or where the site sits in a conservation area, green belt or coastal location. Existing leisure use can help, but it does not guarantee that a new structure is permitted. The consistent advice across planning guidance is to seek pre-application advice from the local planning authority before spending, and to find that authority through the gov.uk planning portal.

Building regulations.

Planning permission and building regulations are separate. A fixed structure with plumbing and electrical installations falls under building regulations regardless of its planning status, and heater clearances, ventilation and certified electrical work need to be signed off by the relevant bodies. This protects guests and, in practice, protects the operator’s insurance.

Licensing, and a London-specific requirement.

There is no single national sauna licence. But in London, Part II of the London Local Authorities Act 1991 defines an “establishment for special treatment” to include premises used for “vapour, sauna or other baths”, and every London borough licenses such premises annually under the Act. Operating without a licence is an offence, with boroughs citing fines of up to £5,000. The grounds on which a borough can refuse a licence are instructive for any operator, London or not, because they read like a design checklist: premises not structurally suitable, unsatisfactory lighting, sanitation or ventilation, unsafe means of heating, inadequate fire precautions. Boroughs publish standard licence conditions with a dedicated part covering premises where sauna is practised, and licence fees are modest, with Hounslow’s 2026 to 2027 schedule placing saunas in a category at £434 for a new licence.

Outside London there is no equivalent general scheme, but licensing requirements vary by council, and a conversation with the local authority’s licensing team belongs in the feasibility stage, not after opening.

Water and insurance.

Where cold plunges are shared rather than single-use, water treatment falls within the territory of the Pool Water Treatment Advisory Group, the UK’s reference body for pool and spa water quality, and their guidance should inform the specification. Public liability insurance is essential, and employers’ liability insurance is a legal requirement where staff are employed.

In practice, a design consultancy’s role here is to coordinate the planning submission and licensing application alongside the design, and to appoint the specialist sauna supplier and the principal contractor who carry out the works under their own contracts with the client.

The commercial model

Public session pricing is one of the best-documented parts of the sector, because it is published on every venue’s website and collated by the sauna directories.

Beyond the session, the established venues layer memberships and bulk packages, private group bookings, and paid programming such as Aufguss and guided sessions. For a hotel, the further value is the halo: a social sauna is a reason for locals to visit, a guest amenity that photographs well, and a driver of food and drink spend after the session. Our article on the financial case for hotel spa investment covers that wider commercial framing.

An illustrative capacity model.

The arithmetic is simple enough to run on the back of an envelope, which is the point of showing it. Take the example circuit above: three eight-person cabins, 24 places per session. Suppose the venue runs six timed sessions a day at a blended price of £14. That is 24 places, six sessions, £14, or £2,016 a day at full occupancy. At 60 per cent occupancy across the year, that is roughly £1,200 a day. Substitute your own cabin count, session length, pricing and realistic occupancy, and the model updates. It is an illustration of how the revenue mechanics work, not a forecast, and it excludes the two things a real feasibility study must add: capital cost and operating cost.

On capital cost, honest guidance is that published, verifiable data for permanent commercial sauna installations at UK venues is thin, and figures vary widely with cabin specification, groundworks and services. That is precisely why feasibility work exists. Any number quoted without a project behind it should be treated with caution, including ours.

Risks and the saturation question

The lesson from other rapid-growth leisure formats is that early growth attracts oversupply. London has gone from a handful of public saunas to more than 25 in a few years, with multi-site chains and a not-for-profit operator competing on price. The urban first-mover advantage is closing. That points towards where the opportunity now sits: regional and destination venues with a captive audience, hotels and leisure clubs whose members and guests are already on site, and locations where the nearest social sauna is a long drive away.

Other risks are practical. Outdoor circuits are seasonal in character, though the coverage suggests winter is the peak, not the problem. Guided sessions and Aufguss need trained staff, not just a heater. And a trend is not the same as a habit: the British Sauna Society launched a national bather survey in 2026 precisely to measure whether the surge converts to repeat behaviour, and until that reads out, projections of frequency should stay conservative.

How an existing venue should approach it

The sequence that de-risks this is the same one that applies to any wellness addition, with a few sauna-specific emphases.

1. Feasibility. Is there local demand, and is it already served? What footprint is available, and does it have outdoor space? Can the existing changing rooms take the session-time peaks, or is new provision needed?
2. Concept and format. Bolt-on circuit, converted thermal zone, or standalone bathhouse. This decision drives everything downstream.
3. Design and specification. The circuit ratio, cabin sizing, cooling and rest capacity, accessibility, and how the new offer connects to the host venue, produced through the appointed design team.
4. Planning and licensing. Pre-application advice, the planning submission if required, building regulations, and the licensing conversation with the local authority, coordinated alongside the design.
5. Appointments. The specialist sauna supplier and the principal contractor, appointed by the client and contracted directly, with the consultancy coordinating their delivery against the design.
6. Programming and launch. Session structure, pricing, membership, the guided sessions and events that turn cabins into a venue.

As a design consultancy and project coordinator, Alkaline works across the first five stages, from testing whether the idea fits your site to coordinating the specialists who deliver it

Frequently Asked Questions

Talk to us about adding a social sauna

If you are weighing up whether a communal sauna or bathhouse offer fits your venue, we would be glad to talk it through, from whether the demand exists locally to what your site can realistically hold. Book a consultation, and if you are at the earlier planning stage, our free Spa Project Planning Pack is a useful starting point.

Sources

• British Sauna Society: public sauna site counts (45 in January 2023 to 147 in January 2025, as reported by European Spa Magazine and AP); UK Sauna Map count of more than 600 publicly accessible saunas (PBL Magazine, 2026); operator guidance “Where to start: setting up as a sauna operator in the UK” (January 2026); British Sauna Bather Survey 2026
• University of Greenwich and London Interdisciplinary School research on collective sauna rituals and social connection (2026, reported by the British Sauna Society)
• Time Out London: Community Sauna Baths Walthamstow opening, Arc Canary Wharf and the Sauna Summit (2025)
• Wild Sauna UK: London community sauna guide and pricing check (June 2026)
• IBISWorld: Saunas and Solariums in the UK industry report
• Design for Leisure, “Expert insight: communal bathing design tips”, from the Global Wellness Institute Guide to Hydrothermal Spa and Wellness Development Standards
• Finnmark Sauna: commercial sauna specifications
• Approved Document M Volume 2 (gov.uk)
• London Local Authorities Act 1991, Part II (legislation.gov.uk); borough special treatment licensing pages including Hounslow, Barnet, Wandsworth and Barking and Dagenham
• gov.uk planning portal; Sauna Box planning permission guidance (for the mobile versus fixed distinction)
• Sprintlaw UK: legal requirements for sauna businesses (insurance)
• Pool Water Treatment Advisory Group (PWTAG)