Harvia Cilindro 9kW Black
Fenix touch panel on the wall, plus the MyHarvia app to warm it up from your phone
- Power
- 9 kW
- Stones
- 90 kg
- Supply
- 40 A, 230 V hard-wired
£2.96a session
£38a month
Hekla Cube 250 - 6 Person Outdoor Sauna
Model: HEKLAC250
Regular price £7,299.00
Unit price ⓘ Unit price based on the product measurement shown.
Hekla
A Finnish sauna for 6, with the garden in view
The Hekla Cube 250 is a glass-fronted outdoor sauna with a heat-treated spruce shell and two tiers of smooth aspen benches set out in an L, with room for 6. Light comes in, the heat stays in, and it lives outside all year round.
6people
9 kWrecommended heater
40 mmthermo-spruce shell
- 1Full glass front and 8 mm doorDouble-glazed, tempered glass
- 2Rear panelHalf panoramic window or full timber
- 3Roof shinglesBitumen shingles over an underlay
- 4LED bench lightingBuilt in, with a switch
- 540 mm thermo-spruce shellHeat-treated for rain and frost
- 6Steel bandsTwo bands hold the staves tight
- 7Three foundation beamsLift the shell off the base
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Glass front, garden view
A double-glazed glass front and an 8 mm tempered glass door keep the garden in sight while you sit in the heat.
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Thermo-spruce that stays stable
The 40 mm shell is heat-treated spruce, which Hekla uses so it stays stable through rain and frost. It weathers naturally, with no painting needed.
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Choose your rear panel
Pick a half panoramic window for light from both sides, or a full timber back for more privacy.
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Two tiers of aspen benches
An upper and a lower bench run along the back and down one side in an L. They are thermo-aspen: smooth, splinter-free and resin-free.
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Electric or wood-fired heat
Choose a Harvia Cilindro 9 kW with simple dials, the black 9 kW with the Fenix Wi-Fi panel so you can warm it up from your phone, or the Harvia Linear 18 wood burner for a real fire.
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Ready for evenings
LED lighting built into the benches and a ventilation valve make after-dark sessions calm, with fresh air coming through.
Why people love a garden sauna
- A proper switch-off
- Twenty minutes of dry heat is a simple way to wind down after a long day.
- Warm whatever the weather
- Wet, cold or dark outside, it is a warm place to be in minutes, not hours.
- Time together
- Room to talk, with no screens and no distractions.
- Hot and cold
- Pair it with a cold shower or an ice bath for the full Nordic routine.
What the Cube 250 needs from your garden
It is a small building, so plan the base, the space around it and the power before it arrives.
A firm, level base
A concrete slab or a pile foundation that lets rain drain away. The sauna sits on three supplied beams and Hekla says it can weigh up to about 600 kg once built, plus the people inside. Don't stand it on grass or soil.
Space around it
Plan for about 234 × 250 cm including the roof, and leave room to walk round it for maintenance. We suggest at least 50 cm. At 235 cm tall it is under the usual 2.5 m height limit for garden buildings near a boundary, but check with your local council.
Power, or a flue
An electric heater is hard-wired by a qualified electrician on its own 40 A supply from your consumer unit. The Linear 18 wood burner needs no electrics, just its chimney through the roof, which comes in the kit.
225 × 250 × 235 cmWidth, depth and height
217 × 220 cmInside, wall to wall
6 peopleSeats, on two tiers
Up to 600 kgBuilt weight, before people
Built for a British garden
What is in the walls, the glass and the roof, and why it matters when it lives outside all year.
How the Cube 250 is built
Shell
40 mm heat-treated spruce.
Heat treatment changes the wood so it takes in less water and moves less. Hekla uses it so the shell stays stable through rain and frost, and it weathers naturally without paint.
What to watch for elsewhere
Untreated softwood.
Plain spruce or pine soaks up rain, swells and shrinks, and needs regular treatment to stop it cracking.
How the Cube 250 is built
Shape
Interlocking staves, held by steel bands.
Each curved stave locks into the next, and two steel bands pull the shell tight, so the shape holds as the timber settles.
What to watch for elsewhere
Screwed flat panels.
Flat boards rely on screws and joints, which can open up as the timber moves with the seasons.
How the Cube 250 is built
Glass
Double-glazed front and an 8 mm tempered door.
Two panes with a gap between them keep more heat in than one, and tempered safety glass is made for sauna temperatures.
What to watch for elsewhere
Single, thin glass.
A single pane lets heat out quickly, so the room takes longer to warm up and costs more to run.
How the Cube 250 is built
Roof
Bitumen shingles over an underlay.
Overlapping shingles shed rain and snow off the curved roof, with an underlay underneath as a second barrier.
What to watch for elsewhere
Bare timber on top.
Without a proper covering, the top of the sauna takes the full force of the weather.
How the Cube 250 is built
Benches
Thermo-aspen, on two tiers.
Aspen is smooth, splinter-free and resin-free, so the benches, backrest and floor are comfortable on bare skin. Sit up high for more heat, lower down for less.
What to watch for elsewhere
One flat bench.
With a single bench everyone sits at the same height, so there is no choosing a cooler or hotter spot.
Your heater and what it costs to run
Choose a Harvia Cilindro electric heater or the Linear 18 wood burner. Glass loses more heat than timber, so Hekla pairs these cubes with 9 kW or more. Pick one above and the figures here follow your choice.
Recommended
Harvia Cilindro 9kW
Dials on the heater for heat and timer
- Power
- 9 kW
- Stones
- 80 kg
- Supply
- 40 A, 230 V hard-wired
£2.96a session
£38a month
Harvia Linear 18 Compact
A real wood fire, no electrics needed
- Power
- 14.3 kW
- Supply
- None, plus a flue through the roof
Logsabout an armful a session
How we work this out: a 45-minute warm-up at full power, then a one-hour session with the heater on about half the time, so about 1.25 hours at full power. Electricity at 26.32p per kWh, the Ofgem price cap from October to December 2026. A month is 4.3 weeks. Your costs depend on your tariff, the weather and how hot you like it.
Your first sauna session
There is no wrong way to sauna, but this simple rhythm is how most Finns do it. It is a little different with the wood burner, so pick your heater.
- Warm it up
Switch on 30 to 45 minutes before. Most people enjoy 70 to 90°C. Take a quick shower first.
- Sit in the heat
Stay 8 to 15 minutes. Sit higher for more heat, lower for less. Ladle a little water on the stones for a burst of soft steam.
- Cool down
Step out for a cold shower, a dip in an ice bath or just fresh air.
- Rest and repeat
Sit down, drink some water, and when you are ready go back in. Two or three rounds is plenty.
- Light the fire
Light the burner about an hour before, with small dry kindling first and then a few logs. Most people enjoy 70 to 90°C.
- Sit in the heat
Stay 8 to 15 minutes. Ladle a little water on the stones for soft steam, and add a log now and then to keep the heat up.
- Cool down
Step out for a cold shower, a dip in an ice bath or just fresh air.
- Rest and repeat
Drink some water and go back in when you are ready. When you have finished, let the fire burn down on its own.
A 2-year Hekla warranty
Covered by the brand, backed by our team.
Your Hekla Cube 250 comes with Hekla's 2-year warranty, and your Harvia heater is covered by Harvia. If anything goes wrong, call us first and we'll sort it out with the maker for you.
Brand warranty
Help from our UK team
Easy to look after
A few simple habits keep it looking good and smelling fresh.
Sit on a towel
It keeps the benches clean and stops sweat marks soaking into the wood.
Let it dry out
After a session, leave the door ajar for a while so the inside dries. Don't use cleaning products inside.
Check the stones
Re-stack the heater stones once a year and replace any that have crumbled, so the heat and steam stay even.
Let the outside weather
The thermo-spruce turns a silvery grey over time. That is normal. In heavy rain a little water can seep into the staves; it dries out when you heat the sauna.
What our customers say
Rated by our customers
Independent reviews from people who bought from us, collected and shown by Trustpilot.
Who we work with
Hull FC
Hull City
Queens Park Rangers
DIY SOS The Big Build
Delivery and installation
Hekla saunas come direct from the maker. Here is how it gets to your garden.
Order online
Choose your finish, rear panel and heater and place your order. Nothing is sent automatically.
We call you
Our team phones to check access, your base and your electrics, and to agree a delivery date.
It arrives
Flat-packed at the kerb, or delivered and built on your base by our installers.
Choose how far we take it
Pick your option at checkout.
Flat-pack kerbside delivery
Build it yourself£149Arrives packed on a pallet at the nearest accessible point outside your property. The manual takes you through the build. It is a job for two people.
Delivery and installation
We build it for you£899Our installers deliver the sauna, build it on your prepared base and connect the heater. Just have the base ready.
Tight access, such as a narrow side path, may affect delivery, so tell us about it when we call. Read the delivery guide
Questions people ask
The things people usually want to know before they buy.
How many people fit?
Hekla says 6, on an upper and a lower bench set out in an L.
Electric or wood burner?
Electric heats up with less fuss and the black Cilindro can be started from your phone. The Linear 18 wood burner gives a real fire and needs no electrician, but you light it and add logs. Both have stones for steam.
How long does it take to heat up?
About 30 to 45 minutes with an electric heater, depending on the weather outside. A wood fire takes a little longer.
Can I pour water on the stones?
Yes. Every heater we offer with it holds stones. A ladle of water on the hot stones makes a burst of soft steam, called löyly.
Do I need an electrician?
For an electric heater, yes, unless you choose delivery and installation: our team connects the heater for you. The wood burner needs no electrics.
Does it need planning permission?
Garden buildings under 2.5 m tall near a boundary usually don't, and this sauna is about 235 cm tall. Rules vary, so check with your local council, and check any rules about wood burners and smoke in your area.
Can it stay outside all winter?
Yes, it is built to stand outside all year. In heavy rain a little water can seep into the staves; this is normal for a timber sauna and dries out when you use it.
What is the difference between Scandi and Nero?
Scandi is natural thermo-spruce. Nero is the same sauna with a black finish outside. The inside is the same in both.
Full specifications
Everything about the Hekla Cube 250 in one place.
Size and weight
- Outside
- W 225 × D 250 × H 235 cm
- Inside
- About 217 × 220 cm
- Built weight
- Up to about 600 kg
- Capacity
- 6 people
Build
- Shell
- 40 mm thermo-spruce staves
- Roof
- Bitumen shingles over an underlay
- Bands
- 2 steel bands
- Foundation
- 3 foundation beams
- Benches and floor
- Thermo-aspen, two tiers in an L, with backrest and duckboard floor
Glass
- Front
- Double-glazed full glass front
- Door
- 8 mm tempered grey glass
- Rear panel
- Half panoramic double-glazed window or full timber
Inside
- Lighting
- Integrated LED bench lighting
- Ventilation
- Ventilation valve
Heater
- Electric
- Harvia Cilindro 9 kW with dials, or 9 kW black with Fenix Wi-Fi, 90 kg stones
- Wood
- Harvia Linear 18, 14.3 kW, 40 kg stones, chimney kit included
- Supply
- Electric heaters hard-wired, 230 V, 40 A
Finish and warranty
- Finish
- Scandi (natural) or Nero (black)
- Warranty
- 2 years from Hekla
Sizes are from Hekla's spec sheet and drawing. The bench layout in our plan follows Hekla's drawing. Running costs are estimates.