The best indoor saunas in the UK

The 2030 is built in Wolverhampton by Oceanic Saunas, which has made saunas since 1982, and it arrives as factory-made wall and ceiling panels, 50mm thick, insulated and already clad in spruce. It measures 1,983mm by 1,368mm and 2,020mm tall, which seats three and gives the top bench room for most adults to lie down.

From £3,184 buys the cabin, a spruce bench kit, a 4.5kW Oceanic heater with external controls and the accessory pack: the whole sauna, not a shell. A glass door, a full glass front or a glass front and side are configurator options, bronze glass costs the same as clear, and hemlock cladding roughly doubles the timber cost.

Oceanic builds to order in 6 to 7 weeks and recommends a carpenter, because the panels come made up but the benches, backrest and floor mats are assembled on site. The heater costs about £1.18 an hour at full power and is hard-wired by an electrician.

The Traditional 160 is the best-finished cabin under £5,000 here: a full front of 8mm grey safety glass, thermo-aspen inside, LED light under the benches and a 6kW Harvia The Wall heater with Harvia's Fenix Wi-Fi panel, so it can be warming up while you drive home. It costs £4,899 with that heater, or £4,999 with the 9kW version.

The catch is height. The cabin is 2m tall and Hekla wants 50cm clear above it for the roof panel and wiring, so the room needs a ceiling of about 2.5m, which rules out many loft rooms and basements. The 6kW heater also asks for a 40A supply, where the 6kW heaters in the CenturaHeat and Finnmark cabins ask for 32A.

Outdoor Living delivers it flat-packed to the kerb for £149 or brings it in and builds it for £399. Hekla's warranty is 2 years, and Harvia covers the heater.

Four seats on opposing two-tier benches, a full-height glazed double-door front and a 6kW Harvia BC60E with an external control panel, for £4,417.82, down from £5,197.44. The cabin is Canadian hemlock, 1,800mm by 1,500mm and 1,900mm tall, the lowest cabin on this page.

Two things hold it back. Pro-Line says the four-person figure comes from the illustrated seating rather than a stated occupancy rating, and the listing gives no wall thickness or insulation detail, where Oceanic and Harvia both describe insulated panels. Oceanic's 4-person 2525 is also £1,290 less, though its base price buys a glass door rather than a glazed front. The heater needs a 32A circuit, and Pro-Line's instructions call for at least two people to lift and secure the glass front.

The Variant is Harvia's element cabin, and the smallest size stands on 1,150mm square and 2,030mm tall. Pool and Spa Centre now sells it with a 3.6kW Harvia Delta heater and stones included at £4,205.33, along with upper and lower abachi benches, a glass door, a heater guard and an equipment pack with the light, bucket, ladle and thermometer.

Harvia calls the cabin completely insulated and gives its room volume as 3.48m³, which is why 3.6kW is enough. The trade is space for the money: £4,205.33 is £2,064 more than Oceanic's 1520, which takes slightly more floor, and Harvia doesn't give a seating number. The 1,150mm size was on back order on 21 October, and Harvia's manual asks for a room at least 2,150mm high.

Finnmark's Indoor Cube is made in Estonia from 40mm thermally modified spruce, with an 8mm tempered glass door and front, two tiers of thermo-aspen bench and a 121cm bench length. It's £4,993.99 without a heater, down from £5,493.99, or £5,522.99 with a 6kW Narvi NM and stones.

It's the tallest cabin here at 221cm, so Finnmark asks for a 230cm ceiling, 150mm clear on every side and a floor that can carry 450kg. It ships as one box 209cm long, which has to get through the hallway and up any stairs before you can build it.

Finnmark says most buyers assemble it themselves in a weekend. The 6kW heater needs its own 32A circuit.

The Fenix is Harvia's black cabin: black-treated spruce outside, aspen inside, and a front of two 8mm glass panels around an 8mm glass door. The walls are about 75mm thick with glass fibre insulation behind an aluminium foil vapour barrier, the most detailed wall build any seller here publishes, and the top bench is 1,865mm long and 600mm deep, room to lie flat.

£8,737.18 includes a Harvia Virta heater with the Xenio controller, stones and an accessory pack, and the 2,060mm by 2,033mm size is £9,345.40. Pool and Spa Centre doesn't state the heater's output, so ask before you book the electrician. Both sizes were on back order on 21 October, and Harvia's manual asks for a room at least 230cm high and 5cm of space between the cabin and the walls.

The cheapest complete 2-person indoor sauna we found: £2,141 for Oceanic's 1520, a 2-person cabin 1,368mm long and 1,060mm deep with a 3kW heater, built-in digital controls, a bench kit and accessories. It uses the same 50mm insulated panels and 5-year timber warranty as the 2030 above.

The saving over the 2030 is £1,043, and what goes is the third seat and the length to lie down. The 3kW heater costs about 79p an hour at full power. If two of you want to stretch out, the 1,983mm-long 1530 is £2,651. It's built to order like every Oceanic cabin, so allow 6 to 7 weeks.