ThermaSol Fortis 3-4 Person Outdoor Sauna Cabin
ThermaSol Fortis 3-4 Person Outdoor Sauna Cabin
- Regular price
- $36,619.00
- Regular price
- $52,312.86
- Sale price
- $36,619.00
- Unit price
- per
Found it lower? We'll match it, before or after you buy.
Send us a link to the lower price. If it is the same model, new and in stock at an authorized U.S. online retailer, we match it. Already ordered? If it was lower on your order date, claim the difference within 30 days.
Excludes sale pricing, marketplace sellers and later price drops.
Read the full price match terms →Fifty-four square feet under an eave-style roofline.
- Largest interior of the two mid-size cabins
- 110 x 106 in placement clearance, 2,161 lbs assembled
- Harvia Virta 8 kW and Fenix control fitted
Preorder — ships 12 weeks
This item is currently out of stock. Our next shipment arrives in 12 weeks, and orders ship in the order they were placed.
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How does delivery work?
How does delivery work?
Freight, quoted for your address. These are crated units of roughly 1,300 to 4,800 pounds going to residential addresses, so there is no flat rate. Send us your postcode before you order and we will come back with a real figure.
The outdoor cabins arrive fully assembled. All eight travel as one piece, so there is no build on your weekend, but a forklift or crane has to reach the pad. Measure the gate, the side return and anything overhead first.
The indoor cabins arrive in panels. The Lumaria, Aalto and Astra are built in place by two to four people. What matters is the route in, not the room itself.
Delivery is curbside and someone has to be there. The carrier calls to book a window and brings it to the kerb or driveway. Moving it onto the pad is yours to arrange.
Inspect before you sign. Note any damage on the delivery paperwork while the driver is there, photograph everything, and tell us within 48 hours. Refuse a structurally damaged crate and call us.
Lead times. Twelve weeks on every outdoor cabin, four to eight on the three indoor models, built to order from the day you order.
What does the warranty cover?
What does the warranty cover?
Two warranties, not one. ThermaSol covers the sauna room and Harvia covers the heater inside it. They differ in length and they are claimed in different places.
The sauna room: 1 year. From substantial project completion, covering defective workmanship and materials such as mis-cuts, rough lumber or knot loss.
The heater, control and power box: 5 years residential. One year in a commercial setting. Stones and heating elements carry one year either way.
Two conditions decide most claims. The room must be registered within 15 days of purchase, and installed by a certified electrician or qualified service representative.
Commercial use voids it. ThermaSol excludes residential units used in any non-residential setting, naming hotels, spas, gyms, health clubs and short-term rentals. Tell us before you order and we will quote a range that is warranted for it.
Who you call. Cabin claims go through ThermaSol and we start them for you. Harvia heaters are serviced by Harvia US directly, which is a separate route.
What if I need to return it?
What if I need to return it?
30 days from delivery. Cancelling before it ships costs nothing at all, and on a twelve week cabin there is usually room to change your mind.
Condition required. As new, unused, unassembled and in its original packaging with every component. Once a unit has been sited, connected or assembled it is no longer returnable.
Get an authorisation first. Contact us with your order number, we raise it with ThermaSol, and you ship within 14 days with the authorisation number written on the crate.
What a return costs. A restocking fee of up to 5% may apply and you pay the return freight, which is substantial on a crated sauna. We do not deduct the original outbound shipping. Ask us for an estimate before you commit.
Damaged on arrival is a freight claim, not a return. Note it on the paperwork while the driver is present, photograph it before anything moves, and tell us within 48 hours. Handled that way it costs you nothing.
Refunds. To the original payment method once the unit is received and inspected, normally within 5 to 10 business days.
PRODUCT DESCRIPTION
Jump to11 sections
The short answer
The ThermaSol Fortis is a 3 to 4 person outdoor sauna with the deepest footprint in its class
Fifty-four square feet inside, under an eave-style roofline that reads more like a garden building than a cabin. The Fortis arrives finished, which takes the build out of your weekend and replaces it with a lifting job and an electrician.
The ground
110 × 106 in
ThermaSol's placement clearance. The cabin itself is 87 inches wide by 90 deep, so this allows roughly two feet of working room on the plan and the service access the warranty depends on.
The room
54 sq ft
Cabin interior, for 3 to 4 people. Thermo aspen benches and backrest against Tyrol wood walls, over a high density resin composite floor.
The circuit
240V, 33.4 A
The 8 kW Harvia Virta draws 33.4 amps on a 240 volt single phase supply and wants a minimum 8 AWG 90 °C copper feed. Your electrician sizes the breaker.
Inside the cabin
Fifty-four square feet, and the dimension ThermaSol leaves out
ThermaSol publishes the Fortis interior as an area, 54 square feet, and stops there. Interior width, depth and height are not published for this cabin or for any cabin in the range. If your plan depends on a particular bench run or a particular headroom, that number does not exist in any ThermaSol document we hold and we will not estimate it. Ask us and we will put it to ThermaSol in writing.
The finishes are published. Benches and backrest are thermo aspen, the walls are Tyrol wood, and the floor is a high density resin composite rather than timber. A full spectrum LED strip runs in the backrest on its own controls, separate from the integrated cabin lighting.
Where the extra three square feet go
The Fortis is three square feet larger inside than the Spectra and five inches wider outside, on a footprint that is sixteen inches deeper at the clearance line. It is the deeper of the two rather than the taller: ThermaSol asks for 95 inches of height clearance here against 100 for the Spectra.
Before you order
Five checks that are cheap now and expensive later
1. The pad
2,161 pounds assembled, 2,381 in transit. Site it on a level, drained base rated for that load. If the plan is a deck rather than a slab, have the structure confirmed before you order rather than after the truck is booked.
2. The approach
The Fortis is delivered fully assembled, so a forklift or crane has to reach the pad. Measure the gate, the side return and anything overhead.
3. The clearance
110 inches wide by 106 deep by 95 high. The depth is the one that catches people out: this cabin wants more room front to back than its siblings.
4. The electrician
ThermaSol requires a licensed electrician for the heater installation. Book that person against the delivery date.
5. The lead time
Twelve weeks. Built to order, so this is a plan-ahead purchase.
How it is built
What ThermaSol publishes about the Fortis, and what it does not
The envelope
Multi layer construction with wood fibre insulation, under what ThermaSol describes only as a durable weather resistant roof. Unlike the Spectra, no roof membrane is named for the Fortis, and we are not going to borrow its sibling's specification to fill the gap.
The exterior, and why there is no species on this page
ThermaSol gives two different answers. The product page says thermally modified and brushed Nordic spruce or pinewood. The spec sheet says Tyrol wood with a black trim inset and honed black aluminium cladding. Those are not the same material. Until ThermaSol reconciles them we are publishing neither, because a wood species is exactly the kind of fact a buyer repeats to a builder.
The glass
Parsol dark grey, semi private, argon insulated and UV protected. ThermaSol quotes two different thicknesses for this same named glass across sibling models, so no millimetre figure appears here either.
The door
Aluminium framed glass with hidden hinges, in a single configuration. There is no left or right hand choice on the Fortis, unlike the Vue and the Vera.
Heater and circuit
An 8 kW Harvia Virta, and a spec sheet that gets it right
The Fortis ships with a Harvia Virta, ThermaSol part 14-HL8U1UL, under a Harvia Fenix control with a twelve hour delay start, plus three boxes of Olivine Diabase dark grey stones totalling 110 pounds, a temperature sensor, two headrests and a wood platform.
Harvia's North American manual Y05-0767 lists HL(S)8U1 at 8.0 kW, drawing 33.4 amps at 240 volts single phase on a minimum 8 AWG conductor rated to 90 °C.
Worth knowing if you are cross-shopping the Spectra
ThermaSol's three outdoor spec sheets share an identical power block reading Required Power: 8 kW. On the Fortis that figure is correct, because the heater this cabin actually carries is an 8 kW unit. On the Spectra the same line sits under a 9 kW heater and on the Ombra under a 10.5 kW one, where it is simply wrong. If you have been comparing the two cabins on their spec sheets, that is the trap.
Why there is no breaker size here
Harvia does not publish one. None of the three Harvia North American manuals gives a fuse or breaker rating for any heater in this family. They publish current draw and a minimum conductor gauge and leave the overcurrent device to the installer. Your electrician sizes it against 33.4 amps under the NEC and local code.
Harvia does give one instruction plainly, in section 3.7: the heater feed must not run through an RCD or GFI.
Is 8 kW enough for 54 square feet
Harvia publishes a floor area range of 28 to 69 square feet for the 8.0 kW Virta. Fifty-four sits inside it with margin at both ends.
Running cost
What an hour in the Fortis costs to heat
An 8 kW element runs flat out while the room comes up, then cycles to hold temperature. Across a typical hour, counting both phases, budget roughly 4.8 kilowatt hours.
At 17 cents a kilowatt hour that is about $0.82 an hour of use. Put your own rate in, because it moves the answer more than anything about the cabin does. Three one hour sessions a week lands near $11 a month at that rate.
What you get
What arrives, and what is separate
In the delivery
The assembled cabin with the Harvia Virta fitted, the Harvia Fenix control, a temperature sensor, 110 pounds of Olivine Diabase stones, two headrests and a wood platform. The Fenix pairs with the MyHarvia app.
Not in the delivery
The base, the electrical supply and the electrician, the machine that lifts it into place, and site preparation. Freight on a cabin this size is quoted rather than published, so speak to us before ordering and we will get a real number for your address.
Delivery and siting
It arrives built, which changes the job
Most outdoor saunas near this price are a flat pack with a two day assembly. The Fortis is not. It leaves the distributor finished and arrives as one 2,381 pound unit, which removes the build and replaces it with a lifting problem.
Plan for machine access to the pad, an approach wide enough for the cabin plus rigging, and someone on site to direct placement. Once it is down and level the remaining work is the electrical connection and filling the stone basket.
Keep the service clearance honest. ThermaSol's 110 by 106 inch footprint is not decorative: an installation that leaves no access to the heater is excluded from the warranty.
Specifications
ThermaSol Fortis specifications
| Exterior | 87 in W × 90 in D × 89 in H |
|---|---|
| Cabin interior | 54 sq ft |
| Placement clearance | 110 in W × 106 in D × 95 in H |
| Capacity | 3 to 4 people |
| Assembled weight | 2,161 lb |
| Shipping weight | 2,381 lb |
| Heater | Harvia Virta 14-HL8U1UL, 8.0 kW |
| Supply | 240 V single phase, 33.4 A, minimum 8 AWG 90 °C copper |
| Control | Harvia Fenix, 12 hour delay start |
| Stones | Olivine Diabase dark grey, 3 boxes, 110 lb |
| Interior | Tyrol wood walls, thermo aspen benches and backrest, high density resin composite floor |
| Glass | Parsol semi private dark grey, argon insulated tempered, UV protected |
| Insulation | Multi layer wood fibre |
| Door | Aluminium framed glass, hidden hinges, single configuration |
| Lead time | 12 weeks |
ThermaSol does not publish interior linear dimensions, a roof membrane, a settled exterior wood species or a glass thickness we can stand behind for this cabin. Each is left out above rather than estimated.
Compare models
Where the Fortis sits in ThermaSol's outdoor range
| Model | Exterior | Interior | People | Heater |
|---|---|---|---|---|
| Fortis | 87 × 90 in | 54 sq ft | 3 to 4 | Virta 8.0 kW |
| Spectra | 82 × 90 in | 51 sq ft | 3 to 4 | Virta 9.0 kW |
| Vue | 79 × 87 in | not published | 3 to 4 | Virta 9.0 kW |
| Vera | 63 × 87 in | not published | 2 to 3 | Virta 8.0 kW |
| Ombra | 130 × 91 in | 80 sq ft | 4 to 5 | Virta 10.5 kW |
The Fortis and the Spectra are the closest pair in the range, three square feet apart inside. The honest difference is the heater and the roofline: the Fortis is the larger room on the smaller heater, and the Spectra is the smaller room with the named roof membrane. If you want materially more space, the step is the Ombra rather than either of these.
Buyer questions
ThermaSol Fortis questions buyers ask before ordering
Does the Fortis come with the heater?
Yes. The Harvia Virta heater, the Harvia Fenix control, a temperature sensor and 110 pounds of stones are included and fitted at the factory. The electrical supply and the electrician are not, and neither is the base it stands on.
What size breaker does it need?
Harvia does not publish one and neither will we. The heater draws 33.4 amps at 240 volts single phase and wants a minimum 8 AWG conductor rated to 90 degrees C. Your licensed electrician sizes the overcurrent device to that load under the NEC and your local code.
How is the Fortis different from the Spectra?
Three square feet more interior, five inches more width and sixteen inches more depth at the clearance line, on a smaller 8 kW heater instead of the Spectra's 9 kW. The Spectra also has its roof membrane named as Firestone EPDM where the Fortis does not. They are genuinely close, and the choice usually comes down to the footprint your garden allows.
What wood is the outside?
ThermaSol gives two different answers. The product page says thermally modified and brushed Nordic spruce or pinewood; the spec sheet says Tyrol wood with black trim and honed black aluminium cladding. We are not publishing either until the manufacturer reconciles them. Ask us and we will get it in writing before you order.
Do I need a concrete slab?
A level, drained base rated for 2,161 pounds assembled. A deck is possible where the structure is rated for that load plus occupants, but have it confirmed before ordering rather than after the delivery is booked.
How does it get into my garden?
On a forklift or a crane. The Fortis arrives fully assembled as a single 2,381 pound unit, so machine access to the pad is a requirement rather than a convenience. Measure the gate and the side return before you order.
What is the warranty?
One year on the sauna room from substantial project completion, and five years on the Harvia heater, control and power box in a residential setting. Stones and heating elements carry one year. Registration is required within fifteen days of purchase and the room must be installed by a certified electrician or qualified service representative.
Can I put it in a rental or a gym?
No. ThermaSol's warranty excludes residential units used in any non residential setting, naming hotels, spas, gyms, health clubs and short term rentals specifically. If the plan is commercial, talk to us and we will quote the right range instead.
Is the Fortis certified?
The Harvia Virta heater fitted inside is ETL Listed to UL 875, the US standard for electric dry bath heaters. No certification is published for the structure itself, which is normal in this category but worth knowing before you speak to a local inspector. A listed heater does not make the structure listed, because UL 875 treats the two as separate things.
