The Outpost Outdoor Garden Sauna

The Outpost: Premium Insulated Outdoor Sauna

The Outpost is a fully insulated, premium build outdoor sauna designed for serious year-round use in any British garden. Built to order in the EU and delivered fully assembled, with your choice of Harvia heater and exterior cladding.

Key features at a glance:

• Capacity: up to 6 people comfortably
• Dimensions: 235 × 235 × 240 cm external, 200 × 200 cm sauna room
• Insulation: 10 cm rockwool to the walls and ceiling for year-round use
• Frame: C24 structural grade calibrated timber
• Exterior cladding: Spruce W-profile (standard), Thermowood W-profile, or maintenance-free WPC composite
• Interior panels: Spruce (standard), with Thermowood, Linden or Alder available as upgrades
• Panoramic window: 200 × 200 cm, 8 mm tempered glass
• Benches: 2-tier Linden wood
• Heater: Harvia Cilindro PC90 9.0 kW electric (app control available as an upgrade) or Harvia Legend 150 wood-burning
• Heat-up time: typically around 30 to 45 minutes on the electric heater

Why The Outpost

Engineered to last in the British climate. Built around a structural C24 calibrated frame and clad in W-profile painted timber, the Outpost is designed to handle wet, cold and unpredictable UK weather. The 10 cm rockwool insulation through the walls and ceiling keeps heat where you want it, which means faster warm-up times, lower running costs and reliable temperature even on a January morning.

Three claddings, three levels of upkeep. The standard build comes in painted W-profile spruce, a classic look that takes paint beautifully and weathers well when maintained. Thermowood is heat-treated to a higher temperature, which removes moisture and resin and gives a darker tone, a harder surface and far better dimensional stability against rot, swelling and warping. Both are timber, and both want retreating every few years to keep looking their best.

WPC composite is the one you never have to touch. Wood plastic composite combines wood fibre with polymer, so it has the grain and warmth of timber with none of the upkeep. No oiling, no staining, no retreating, no silvering, no splitting, no rot. Hose it down when it needs it and that is the entire maintenance schedule. Available in black, grey or brown.

A panoramic view, day or night. The 200 × 200 cm 8 mm tempered glass panoramic window turns your sauna into a viewing platform: your garden, the stars, the snow. Paired with discreet LED lighting beneath the benches and behind the backrest, plus an exterior lights set, it sets the right atmosphere without overdoing the spa resort cliché.

Premium sauna-grade interior. Two-tier Linden wood benches sit inside a spruce-clad sauna room. Linden is one of the classic Finnish sauna woods: light in colour, low in resin, and comfortable against bare skin even when the air is hot.

Your choice of heater. Pick the Harvia Cilindro PC90 9.0 kW electric heater for push-button convenience and digital control, available plug-in ready so it connects the moment it arrives, or the Harvia Legend 150 wood-burning stove (chimney included) for the traditional Finnish ritual. Both are properly specified for the cabin volume.

Made bespoke to your taste. Beyond the heater and exterior cladding choices, the Outpost can be further customised with your choice of exterior paint colour, interior sauna room wood, door style, and add-ons like a Himalayan salt wall, sauna accessory set, water tank or wooden heater fence. See Bespoke upgrades below for the full list.

Delivered fully assembled. The Outpost is built, finished and quality checked before despatch and arrives on site ready to position, with no on-site construction. Because it ships as a complete cabin it has to be lifted into place. We can deliver by HIAB lorry-mounted crane, help arrange a mobile crane for longer lifts, or deliver on a flatbed to you or your own crane company. We quote delivery to your postcode and access, so there are no surprises later.

What's included as standard

• Full sauna cabin: C24 calibrated structural frame, W-profile painted exterior (spruce or thermowood per variant), spruce interior cladding, terrace board floor
• 10 cm rockwool insulation to the walls and ceiling
• Panoramic window: 200 × 200 cm, 8 mm tempered glass
• Glass entrance door (tempered)
• 2-tier Linden wood benches
• LED lighting under the benches and behind the backrest
• Exterior lights set
• Harvia sauna heater: electric Cilindro PC90 9.0 kW or wood-burning Legend 150 (per variant chosen)
• Distribution board (electric variant) with RCD protection and separate circuits for heater and lighting
• Chimney (wood-burning variant only): through-roof flue kit

Specifications

Dimensions

Construction & insulation

Heaters

Lighting

• LED strip under benches
• LED strip behind backrest
• Exterior lights set

Capacity

4 to 6 people seated comfortably. The 4 m² internal floor area gives ample room for the heater, two-tier benches and movement space without crowding.

Bespoke upgrades & customisation

Beyond the heater and cladding choices you make at order, almost every other element of the Outpost can be specified to your project. Talk to us when you place your order and we'll confirm the build before fabrication.

WPC colour: If you choose WPC composite cladding, tell us whether you want black, grey or brown when you order. All three are the same price.

Exterior paint colour: a choice of finishes including natural oiled, coal black, golden brown, mahogany, transparent grey, anthracite, light brown, dark grey, dark oak, dark walnut and teak.

Interior sauna room wood:

• Spruce (standard)
• Thermowood (upgrade)
• Linden wood (upgrade)
• Alder wood (upgrade)

Bench wood: Linden or aspen (light tone, standard) or alder (darker tone, on request).

Heater upgrades: beyond the standard PC90 and Legend 150, larger Harvia electric (Cilindro PC90XW 9 kW WiFi, SP90XW WiFi, Legend PO110XW 10.8 kW WiFi) and wood-burning (M3, M3 SL, 20 Pro, 20 Pro SL, Cilindro 16, Legend 300) options are available on request.

Door options: Glass (standard), wooden, or full-glass doors. Window and door glass available in black or mirrored finish (+£300).

Accessories add-ons available:

• Himalayan salt wall with LED
• Sauna accessory set (bucket, scoop, thermometer, timer)
• 30 L or 60 L water tank for chimney (wood-burning only)
• Wooden heater fence

Electrical connection: plug-in ready, hardwired into the distribution board, or cable only. See the electrical supply question below.

For pricing on any of the above further upgrades, contact our team when you order and we'll confirm everything on the spec sheet before fabrication begins.

Frequently asked questions

How many people does it seat?
Four to six adults comfortably, or two people lying down on the two-tier bench setup. The 4 m² internal floor area leaves room for the heater, free movement and a relaxed experience without crowding.

Can I use it year-round?
Yes. The 10 cm rockwool insulation through the walls and ceiling makes the Outpost a true four-season sauna. Warm-up times stay fast and running costs sensible even in deep British winter.

How long does it take to heat up?
With the electric heater, typically around 30 to 45 minutes to bathing temperature. The exact time depends on the outside temperature, how cold the cabin is when you start and the temperature you want. With the wood-burning stove it depends on how the fire is built and fed.

What's the difference between spruce, thermowood and WPC?
Spruce is a classic, lighter softwood that takes paint beautifully and forms the standard exterior cladding. Thermowood is heat-treated to a higher temperature, which removes moisture and resin and gives the wood a darker tone, harder surface and significantly better dimensional stability, so it resists rot, swelling and warping. WPC composite is wood fibre bonded with polymer: it looks like timber but behaves like a manufactured material, so it never needs oiling or retreating, will not rot or split, and holds its colour rather than silvering. Spruce and thermowood are the choice if you want real timber and do not mind maintaining it. WPC is the choice if you want to install it and forget about it.

What's the difference between the electric and wood-burning variants?
The electric variant uses the Harvia Cilindro PC90 (9.0 kW): set the temperature and it heats itself, with app control available as an upgrade. The wood-burning variant uses the Harvia Legend 150 with a through-roof chimney: a more traditional Finnish experience with the sound and smell of a real fire, but it needs lighting and feeding with firewood.

What kind of base do I need?
A flat, level base capable of supporting roughly 1,000 kg installed weight. A concrete pad, paving slabs, or a suitably reinforced timber deck all work. We'll discuss site requirements at the order stage.

How is it delivered?
UK-wide. The Outpost arrives fully assembled as a single unit weighing roughly 1,000 kg, so it has to be lifted into place. Depending on your access we can:

• deliver by HIAB lorry-mounted crane, the usual choice where the lorry can park close to the final position
• help arrange a mobile crane where the lift is longer or has to clear a house or obstacles
• deliver on a flatbed if you have a forklift or telehandler on site
• deliver to your own crane company's depot if you already have someone local

Send us photos of your access and we'll recommend the right option and quote it to your postcode. Lead time is typically 6 to 8 weeks from order, as each unit is built to order with your chosen heater, cladding and finish.

What electrical supply does it need?
The 9 kW electric heater needs one dedicated supply from your house: single phase on a 40A circuit, or three phase at around 13A per phase. Three phase is not required. Your electrician sizes the cable for your run. Every electric Outpost has a distribution board on the outside of the cabin, with RCD protection and separate circuits for the heater and the lighting. You choose how it connects:

• Plug-in ready: the distribution board is fitted with a plug. Your electrician prepares the dedicated supply and socket before delivery, so on the day the sauna simply plugs in. Works on a single phase or three phase supply.
• Hardwired: your electrician runs the supply straight into the distribution board.
• Cable only: supplied with cable tails for your electrician to connect as they prefer.

We send the heater documentation to your electrician before installation. The wood-burning variant only needs power for the LED lighting and exterior lights.

What's the warranty?
5-year manufacturer warranty covers structural and material defects not caused by natural wear and tear. Heater warranty is provided by Harvia direct. Full warranty terms are confirmed at order stage.

What maintenance does it need?
With spruce or thermowood cladding, expect to retreat the exterior paint every few years to keep it looking its best. With WPC composite cladding there is no exterior retreatment at all, a rinse down is enough. In all cases, clean the bench wood periodically and follow Harvia's guidelines for the heater. Wood-burning chimneys should be swept annually.