Sauna installation in London: what it costs, what's involved and what to check

Expect £4,000–£12,000 fitted for a garden sauna in London, and £2,500–£8,000 for an indoor cabin in a spare room or loft. The cabin itself is priced the same in Croydon as it is in Carlisle. What makes London different — and what actually moves your quote — is getting a 2.4-metre structure into a garden you can only reach through your hallway, and then getting a borough with dense conservation-area coverage to leave you alone.

Restore Rooms does not install saunas. This page sets out what a London installation involves and what to check before you commit; if you want prices, we put your enquiry in front of installers who cover your part of the city.

Access is the London problem, and it is the expensive one

London’s gardens are the smallest in Great Britain. The median private outdoor space in the capital is around 140 m² against roughly 188 m² nationally, and roughly one Londoner in five has no access to a private or shared garden at all. But size is rarely what kills a sauna project here. Route is.

The dominant London typology — the Victorian or Edwardian terrace, mid-terrace or end-terrace with a side return — very often has no vehicular or even pedestrian rear access. The only way from the pavement to the lawn is through the front door, down a hall, through a kitchen and out a set of bifolds. That rules out the pre-built barrel or cube that a suburban installer would craning off a trailer in twenty minutes.

Three realistic answers, in rough order of cost:

• Flat-pack or panelised cabin, carried through. Panels sized to pass a standard 762 mm internal door. Adds assembly time on site but no plant hire. This is what most London terraced installs end up being.
• Crane or hiab over the house. Genuinely viable, genuinely not cheap. You need a lift plan, a road closure or a suspended parking bay from the borough, and a street wide enough to set outriggers. Budget four figures on top before the sauna arrives, and allow several weeks for the permit.
• Stick-built on site. Loose timber, a stud frame, insulation and cladding built in the garden. Slower and more weather-dependent, but everything that arrives fits under one arm.

If you have a side gate, say so on the first call — it is the single biggest swing factor in a London quote. Our where to put a garden sauna guide walks through siting once access is solved.

Delivery costs: ULEZ, the Congestion Charge and the parking bay

The ULEZ now covers every London borough at £12.50 a day for a non-compliant van, operating 24 hours a day, every day except Christmas Day. Most installers running late-model diesel vans are compliant and it never appears on your bill. The Congestion Charge is a separate central-London charge on top, and the rate rose at the start of 2026 — check TfL’s current figure if you are inside the zone.

The charge nobody warns you about is parking. A half-day install in Hackney or Wandsworth with no off-street space means either a suspended bay applied for through the borough, or a visitor permit, or the installer paying for the hours. Ask which, and ask who pays.

Planning: it depends entirely on which borough you are in

There is no London planning authority. Camden, Hackney, Islington, Wandsworth, Lambeth, Southwark, Ealing, Richmond upon Thames, Bromley and the other boroughs each set and enforce their own rules, and the variation is real.

For a house, a garden sauna is normally permitted development: single storey, eaves under 2.5 m, overall height under 3 m for a flat or mono-pitch roof (4 m dual-pitched), no more than half the original garden covered, nothing forward of the principal elevation, and a hard 2.5 m cap if it sits within 2 m of a boundary — which in a London garden it almost always does. The Planning Portal’s outbuildings guidance is the authoritative version.

Two London-specific traps:

Conservation areas. Greater London contains over a thousand designated conservation areas across its 33 districts. Coverage is not evenly spread: Kensington & Chelsea is around 70% designated and Islington roughly 50%, while some outer boroughs are in single figures. Richmond upon Thames has the most individual designations. In a conservation area, an outbuilding at the side of the house stops being permitted development, and many boroughs layer Article 4 directions on top that remove more rights again.

Flats and maisonettes have no outbuilding rights whatsoever. None. If your title is leasehold flat rather than house, a garden sauna is a full planning application plus freeholder consent plus, usually, a licence to alter. Given how much of inner London is flatted, this catches a lot of people. Full detail is on our garden sauna planning permission page.

Hard water, and why it matters more here

London sits on chalk. Thames Water’s supply across most of the capital runs roughly 250–330 mg/l as calcium carbonate — very hard by any classification, and among the hardest supplies in Europe.

For a traditional sauna that matters in two places. Ladle tap water onto hot stones and the calcium stays behind, so London stones fur up and crack sooner and want turning or replacing more often than they would on a soft supply. And where a heater has a sheathed element that gets splashed directly, scale acts as an insulating blanket, making the element run hotter than designed. Neither is dramatic. Both are avoidable: keep a jug of filtered or softened water for löyly, and inspect and rotate the stones a couple of times a year.

Hard water is also an argument for infrared if you were undecided — no stones, no water, nothing to scale.

Electrics in London housing stock

A traditional 6–9 kW heater needs a dedicated circuit; anything from about 4.5 kW upward is normally a three-phase or high-current single-phase job that will not run off a garden socket. In a Victorian terrace with a consumer unit tucked under the stairs and a 60–80 A incoming supply already carrying an induction hob, an EV charger and a heat pump, headroom is genuinely the constraint — not the cable run.

Two London realities: cable routes from a hall consumer unit to the end of a 12-metre garden often mean lifting a period floor or digging a trench through the side return; and flat consumer units in converted houses are frequently undersized for anything above about 3 kW. Get a load assessment before you choose a heater output. The work is notifiable under Part P; our home sauna electrical requirements page covers the spec.

What to ask before you accept a London quote

Ask whether the price assumes side access, and what changes if it does not. Ask who applies and pays for a parking suspension. Ask what the cable route is and whether the supply has been assessed, not assumed. Ask whether the quote includes the base — a level, load-bearing slab or pad — because London gardens are frequently on made ground and rarely level.

Put your numbers into the sauna cost calculator for a starting range, or run the fit checker if you are not sure the thing physically goes where you want it.