Choosing a garden sauna
"Garden sauna" is not a separate kind of heater. It describes an outdoor cabin sited in a domestic garden, and in practice that means a traditional electric or wood-fired Finnish-style cabin, a curved barrel, or a design-led glass-fronted pod. The shapes overlap almost entirely with what sellers call an outdoor sauna, so the form-factor decision is the same one either way. For the full types comparison, including heaters, wood and how the shapes differ, see our outdoor sauna guide. A barrel sauna is usually the best-value way into a garden sauna, because the round shape heats fast and needs almost no groundwork.
What makes this a garden decision rather than a shopping one is everything around the cabin: whether it fits, what it sits on, how you power it, and whether you need permission. Get those right and the sauna itself is the easy part. The rest of this page works through each in turn.
How much space you need, and where to put it
A compact cabin has a footprint from about 2m by 2m, which suits couples and small plots, while a four to five person cabin with a changing area needs noticeably more room. There is no single fixed distance rule, but leave breathing space around the cabin rather than wedging it into a tight corner: you want clearance for ventilation, for maintenance, and for the door to open, plus a sensible gap from fences and neighbours for both courtesy and planning.
If the garden is small, this is where design-led pods and compact cabins earn their price. A panoramic glass front and a contemporary shape can make a two-person unit feel generous on a tight plot. Think too about where you will step out into the cold, because a garden sauna is often half of a contrast therapy setup, with a cold plunge sited alongside it.
The base: level, firm and drained
Every garden sauna needs to sit on a base that is level, firm and well drained. A solid concrete slab is the gold standard, ideally laser-levelled and around 125mm (about 5 inches) thick, but paving or patio slabs, well-compacted gravel, or a structurally adequate deck all work provided they are genuinely flat and stable. The base should be no smaller than the sauna's footprint, including any changing-room extension.
Level really matters. Check across several points with a spirit level, or lay a straight length of timber across the base and watch for rocking, because even a slight slope can cause problems when the cabin is assembled. Good drainage keeps moisture from building up underneath the timber. Avoid a base laid to a drainage fall, and avoid slippery textured stone such as Indian sandstone underfoot. If you would rather not manage the groundwork yourself, a supply-and-install service can handle the base, delivery and electrics as one job (see our installation guidance).
Getting power to the garden
An electric sauna heater draws far more power than a normal 13-amp plug can supply, typically 6kW to 9kW, so it needs its own dedicated circuit run from the consumer unit. A 9kW heater usually needs around a 40-amp single-phase supply, taken out to the cabin in buried armoured cable to an isolator switch. A wood-fired cabin with only LED lighting may need no more than a simple supply, or none at all.
Running a new circuit out to a garden building is notifiable work under Building Regulations Part P in England and Wales, so it must be carried out or certified by a registered electrician (NICEIC, NAPIT or ELECSA) and issued with an Electrical Installation Certificate. In short: an outdoor sauna supply is not a DIY job, and you should budget for a qualified electrician alongside the cabin itself. A wood-fired model trades that wiring for a flue and safe clearances instead.
Do you need planning permission for a garden sauna?
Usually not in England. A garden sauna cabin is normally treated as an outbuilding, and outbuildings generally fall under permitted development, which means no planning application is needed, as long as the build stays within the limits. Under permitted development in England, a garden sauna should:
not sit forward of the principal elevation (the front wall) of the house;
be single storey, with a maximum eaves height of 2.5m and a maximum overall height of 4m for a dual-pitched roof, or 3m for any other roof;
be no more than 2.5m high overall if it stands within 2m of a boundary;
not, together with other outbuildings and extensions, cover more than half the area of land around the original house;
not be used as separate, self-contained living accommodation.
Two situations override all of that. Within the grounds of a listed building, an outbuilding needs planning permission. And on designated land, such as conservation areas, National Parks and Areas of Outstanding Natural Beauty, the rules are tighter. A larger "garden room with sauna" that combines the cabin with living or gym space is also far more likely to raise building-regulations and planning questions than a simple sauna cabin.
These limits apply to England only. Scotland, Wales and Northern Ireland have their own rules, and interpretation varies even within England, so treat the above as a guide and check with your local planning authority before you build.
What a garden sauna costs to run
Running cost comes down to the heater, the session length and your electricity unit rate. A typical 6kW electric heater on a thermostat cycles on and off rather than drawing full power throughout, so a full heat-up-and-session uses in the order of 3 to 5 kWh. At an illustrative unit rate of 25p per kWh, that works out at roughly £0.75 to £1.25 a session; a larger 9kW heater, or a longer sit, pushes it towards £1.50 to £2.00. Over a year at two to three sessions a week, budget roughly £150 to £350. A wood-fired cabin swaps that for firewood, at around £80 to £180 a year.
Guide prices, correct as of July 2026, based on an illustrative electricity unit rate of 25p per kWh. Confirm the current Ofgem price cap rate before budgeting, as the cap changes every quarter. Per-session energy use is an estimate, and guide prices are typical UK costs, not live prices.