ThermaSol spent four decades perfecting commercial steam before turning to saunas, and it shows. The cabin line pairs architect-grade glass design with Harvia heating in eleven models that range from a compact indoor glass box to a panoramic outdoor retreat. This guide walks through every cabin, indoor and outdoor, so you can match one to your space, your climate, and the way you want to use it.
ThermaSol makes three indoor cabins (Aalto, Astra, Lumaria) and eight outdoor cabins (Fortis, Nordic Dawn, Nordic Misty, Ombra, Solaris, Spectra, Vera, Vue). Every cabin is heated by a Harvia heater with a Harvia Xenio digital control, and most arrive flat-packed for straightforward assembly. Choose indoor if the sauna lives inside a finished room; choose outdoor if it sits in the yard, on a terrace, or off a pool deck. From there, the decision comes down to capacity, glass style, and whether you need a wood-look, solar, or modular option.
What sets ThermaSol cabins apart
ThermaSol is best known as one of the most established names in residential and commercial steam, and the company brought that same engineering discipline to its sauna program. Rather than competing on price, the cabins compete on design and build: full-height glass fronts, clean architectural lines, and finish options you do not usually see at this level, from transparent and dark-grey tinted glass to bronze and mirror glazing.
Three things define the line. First, glass-forward design — most cabins use expansive glazing that makes the sauna feel open and turns it into a design feature rather than a wooden box hidden in a corner. Second, Harvia heating throughout — every cabin ships with a Harvia heater and Harvia Xenio digital control, including Wi-Fi on several models, so you are getting a proven, widely-serviced heating system rather than a generic unit. Third, flat-packed delivery — the cabins arrive ready to assemble with installation instructions, which keeps shipping manageable on a premium product and lets you set up without specialized trades in most cases.
Every cabin carries a one-year manufacturer warranty.
Indoor vs. outdoor: the first decision
The single most useful split in the ThermaSol line is where the cabin will live. It changes the construction, the heater sizing, and the lead time.
Indoor cabins (Aalto, Astra, Lumaria) are built for a finished interior space — a primary bathroom, a basement gym, a wellness room. They use transparent glass to stay light and open, run on a Harvia Virta 9kW heater, and have the shortest lead time in the line at roughly four to eight weeks. They are the right pick when the sauna sits inside, protected from weather.
Outdoor cabins (Fortis, Nordic Dawn, Nordic Misty, Ombra, Solaris, Spectra, Vera, Vue) are weather-built for the yard, terrace, or poolside. They use tinted, bronze, or mirror glass for privacy and glare control, span a wider range of sizes and heater outputs, and typically run a twelve-week lead time. This is where the line gets most expressive — the flagship designs and the largest cabins are all outdoor.
How to choose the right cabin
Once you know indoor or outdoor, four questions get you to a specific model.
How many people? Capacities run from a two-to-three person cabin (Vera) up to four-to-five person cabins (Nordic Dawn, Ombra). For a couple or solo use with the occasional guest, a two-to-four person cabin is plenty. For family use or entertaining, size up.
How much space do you have? Footprints range from a compact 63-inch-wide cabin (Vera) to the 130-inch-wide Ombra. Measure your space first, including clearance around the cabin and access for the door swing, then shortlist by footprint.
What look do you want? Glass style is the most visible choice — transparent for an open, gallery feel indoors; dark-grey or bronze tint for privacy and a warmer exterior look; mirror for maximum daytime privacy outdoors. The glass section below breaks this down.
Any special requirement? A few cabins solve specific problems: Solaris runs on solar power for off-grid placement, Nordic Misty is modular so it can grow with you, and Nordic Dawn brings a thermo-pine, wood-forward aesthetic for a more traditional cabin look.
The indoor cabins
Three indoor models, all transparent glass, all Harvia Virta 9kW with Xenio CX45 control, all roughly four-to-eight week lead times.
ThermaSol Astra
The Astra is the cleanest expression of the indoor line — a transparent semi-panoramic glass front on a roughly 85-inch-square footprint, designed to blend into a modern interior rather than dominate it. Brushed wood paneling, thermo-aspen benches, and integrated RGB color light make it as much a design piece as a sauna. The natural choice when you want the sauna visible and integrated into a finished room.
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ThermaSol Aalto
The Aalto shares the Astra's transparent-glass, 3-4 person format on a slightly larger 87-inch-square footprint, with a corner glass treatment that suits a room where the cabin sits against two walls. If you are deciding between the two indoor squares, it comes down to footprint and how the glass corner reads in your space.
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ThermaSol Lumaria
The Lumaria is the most flexible indoor cabin, offered in medium and large footprints so it can seat anywhere from two to five. Its panoramic glass solarium front is the most expansive glazing of the three indoor models, making it the pick when you want the open, light-filled feel of a glass room and need room to size up or down.
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Get PricingThe outdoor cabins
Eight outdoor models, spanning tinted, bronze, and mirror glass, wood-forward and solar options, and the largest cabins in the line. Most run a twelve-week lead time.
ThermaSol Vera
The Vera is the compact outdoor cabin, with a 63-inch-wide footprint that fits tight yards, balconies, and narrow side-yard placements where the larger models will not go. Dark-grey tinted glass gives it privacy and a refined exterior. The right pick for a couple or a small space that still wants a genuine outdoor sauna.
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ThermaSol Spectra
The Spectra steps up to a 3-4 person cabin while keeping the dark-grey tinted glass. It is the mainstream outdoor choice — enough room for a small group, a footprint that works on most patios and terraces, and a clean modern look that sits well in a landscaped yard.
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ThermaSol Fortis
The Fortis is a 3-4 person dark-grey-glass cabin with a slightly deeper, more substantial footprint than the Spectra. If you want the same tinted-glass aesthetic with a more grounded, solid presence in the yard, the Fortis is the one to compare.
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ThermaSol Vue
The Vue is the panoramic-glass standout, using mirror-glazed glass that reflects the surrounding landscape during the day for maximum privacy while letting those inside see out. On a 79-inch footprint with a Harvia Virta 9kW heater, it is the design-led choice for a garden setting where you want the sauna to disappear into its surroundings.
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ThermaSol Ombra
The Ombra is the flagship — a 130-inch-wide cabin with bronze glass, wave-wood detailing, and a Harvia Virta 10.5kW heater, the largest output in the line. It seats four to five and reads as an architectural pavilion rather than a backyard add-on. This is the cabin for a large family, serious entertaining, or a statement installation.
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ThermaSol Nordic Dawn
The Nordic Dawn is the wood-forward outdoor cabin, built in thermo-pine with a front window rather than a full glass face. It seats four to five and runs a Harvia Spirit 9kW heater with Wi-Fi. Choose it when you want the warmer, more traditional Nordic cabin look instead of the glass-box aesthetic of the rest of the line.
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ThermaSol Nordic Misty
The Nordic Misty is the modular cabin, offered in small and medium sizes with safety rails and a choice of Harvia heater — a Spirit 6kW on the small cabin or a Virta 9kW on the medium, both Wi-Fi. Its modular construction makes it the most adaptable outdoor option, and the add-on modules (changing room, lounge, pergola, terrace, privacy fence) let you build out a full outdoor wellness setup over time.
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ThermaSol Solaris
The Solaris is the off-grid cabin. It runs a Harvia KIP 3kW heater powered by an included solar panel and battery kit, so it can go where running electrical service would be difficult or expensive — a far corner of the property, a cabin retreat, anywhere without a convenient hookup. Offered in small and medium sizes for two to five people.
Get PricingChoosing your glass
Glass is the most distinctive part of the ThermaSol line, and the choice is as much about privacy and light as it is about looks. There are four glass treatments across the cabins.
Transparent (Aalto, Astra, Lumaria) is fully clear, used on the indoor cabins to keep a finished room feeling open and bright. It is the gallery look — the sauna becomes a glass feature inside the space. Best where privacy is already handled by the room around it.
Dark-grey tint (Fortis, Spectra, Vera) is the most popular outdoor treatment. It cuts glare, gives daytime privacy from outside, and reads as a refined, modern exterior. The default choice for most outdoor placements.
Bronze (Ombra) is a warmer tinted glass that pairs with the flagship's wave-wood detailing for a richer, more luxurious exterior. The choice when the cabin is a centerpiece.
Mirror (Vue) is the most private daytime option — the exterior reflects the surrounding landscape while occupants see out. Ideal for a garden or poolside setting where you want maximum privacy without blacking out the view from inside.
The Harvia heating system
Every ThermaSol cabin is heated by a Harvia heater paired with a Harvia Xenio digital control — a meaningful detail, because Harvia is one of the most established and widely-serviced sauna heater makers in the world. You are not getting a proprietary, hard-to-service unit; you are getting a proven heater with parts and support readily available.
Three Harvia heater families appear across the line. The Harvia Virta is the workhorse, used on most cabins in 8kW, 9kW, and 10.5kW outputs scaled to cabin size, several with Wi-Fi control. The Harvia Spirit appears on the wood-forward Nordic Dawn and the small Nordic Misty. The Harvia KIP powers the solar Solaris at 3kW, sized for off-grid operation. Most cabins use the Harvia Xenio CX45 control; the Solaris uses the CX170 to manage its solar power system.
The practical takeaway: heater output is matched to cabin volume at the factory, so you do not need to size a heater yourself — but if you are choosing between cabins, the larger Ombra's 10.5kW heater reflects its larger interior, and the solar Solaris trades raw output for the freedom to run without a hookup.
All 11 cabins compared
| Cabin | Placement | Capacity | Glass / finish | Harvia heater | Lead time |
|---|---|---|---|---|---|
| Astra | Indoor | 3-4 | Transparent | Virta 9kW | 4-8 weeks |
| Aalto | Indoor | 3-4 | Transparent | Virta 9kW | 4-8 weeks |
| Lumaria | Indoor | 2-5 | Transparent (panoramic) | Virta 9kW | 4-8 weeks |
| Vera | Outdoor | 2-3 | Dark-grey | Virta 8kW | 12 weeks |
| Spectra | Outdoor | 3-4 | Dark-grey | Virta 8kW | 12 weeks |
| Fortis | Outdoor | 3-4 | Dark-grey | Virta 8kW | 12 weeks |
| Vue | Outdoor | 3-4 | Mirror | Virta 9kW | 12 weeks |
| Ombra | Outdoor | 4-5 | Bronze | Virta 10.5kW | 12 weeks |
| Nordic Dawn | Outdoor | 4-5 | Thermo-pine | Spirit 9kW | 12 weeks |
| Nordic Misty | Outdoor | 2-5 | Modular | Virta / Spirit | 12 weeks |
| Solaris | Outdoor | 2-5 | Solar-powered | KIP 3kW | 12 weeks |
Complete your sauna
Beyond the cabins themselves, ThermaSol offers add-on modules and accessories to build out a full outdoor wellness setup — particularly around the modular Nordic Misty, which accepts a changing room, lounge, pergola, terrace, and privacy fence. You can see the full range on the ThermaSol sauna add-ons page.
If you are weighing ThermaSol against other premium options, our broader best-selling indoor saunas guide and best-selling outdoor saunas guide compare across brands by size, style, and budget.
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Get PricingFrequently asked questions
Are ThermaSol saunas easy to install?
ThermaSol cabins ship flat-packed with installation instructions and are designed for straightforward assembly. Indoor cabins need a suitable interior space and an electrical connection for the Harvia heater; outdoor cabins need a level pad or foundation and, for most models, an electrical hookup. The solar-powered Solaris is the exception and runs off its included solar panel and battery kit. For exact electrical requirements on a specific cabin, request a quote and we will confirm before you order.
What is the difference between the indoor and outdoor cabins?
Indoor cabins (Aalto, Astra, Lumaria) are built for finished interior spaces, use transparent glass, run a Harvia Virta 9kW heater, and have a shorter four-to-eight week lead time. Outdoor cabins are weather-built for the yard or terrace, use tinted, bronze, or mirror glass for privacy, come in a wider range of sizes and heater outputs, and typically run a twelve-week lead time.
What heater comes with a ThermaSol sauna?
Every ThermaSol cabin includes a Harvia heater with a Harvia Xenio digital control. Most use the Harvia Virta in 8kW, 9kW, or 10.5kW depending on cabin size; the Nordic Dawn and small Nordic Misty use the Harvia Spirit; and the solar Solaris uses a Harvia KIP 3kW. Several models include Wi-Fi control. Harvia is one of the most widely-serviced sauna heater brands, so parts and support are readily available.
How many people do ThermaSol cabins seat?
Capacities range from the compact two-to-three person Vera up to the four-to-five person Ombra and Nordic Dawn. The Lumaria, Nordic Misty, and Solaris are offered in more than one size, covering roughly two to five people. Match capacity to how you will actually use the sauna, and remember to leave clearance around the cabin and for the door swing.
Which ThermaSol cabin is best for a small space?
For outdoor use, the Vera has the most compact footprint in the line at 63 inches wide, making it the best fit for tight yards and balconies. Indoors, the Astra is the smallest of the three indoor squares. If you have an unusual space, send us the dimensions and we will recommend the cabins that fit.
Can a ThermaSol sauna go somewhere without electrical service?
Yes — the Solaris is purpose-built for off-grid placement. It runs a Harvia KIP 3kW heater powered by an included solar panel and battery kit, so it can be installed where running a dedicated electrical line would be difficult or costly. The rest of the line requires an electrical connection.
What glass options are available?
Four treatments: transparent (the indoor cabins), dark-grey tint (Fortis, Spectra, Vera), bronze (Ombra), and mirror glazing (Vue). Transparent keeps an interior open and bright; tinted and bronze add privacy and warmth outdoors; mirror gives the most daytime privacy while still letting occupants see out.
How long does delivery take?
Indoor cabins typically have a four-to-eight week lead time. Outdoor cabins generally run about twelve weeks. Lead times can vary, so request a quote for the current estimate on the specific cabin you want, and we will confirm before you order.
What warranty do ThermaSol saunas carry?
ThermaSol sauna cabins carry a one-year manufacturer warranty. For full warranty terms on a specific cabin, request a quote and we will provide the current documentation.
Specifications, capacities, glass options, heater models, and lead times are based on current manufacturer information and are subject to change. Confirm exact details for any specific cabin by requesting a quote. Sauna Republic is an authorized ThermaSol dealer.
