If you search for “Best Outdoor Sauna,” you will be bombarded with “Top 10” lists featuring random models from Amazon to high-end bespoke cabins. The truth is, there is no single “best” sauna. The best sauna for a small urban terrace in London is completely different from the best sauna for a sprawling garden in the Scottish Highlands.
“Best” is subjective, but quality is objective. Whether you choose a barrel, a pod, or a cube, the underlying materials and engineering determine whether your sauna will last 20 years or rot in 2. In this guide, we break down the objective criteria you should use to judge any outdoor sauna, empowering you to find the model that is best for you.
Criterion 1: The Timber Quality (Thermowood vs. Spruce)
The single biggest factor in longevity is the wood.
Standard Spruce: Many budget saunas use untreated Nordic Spruce. It is cheap and bright. However, in the damp UK climate, untreated spruce acts like a sponge. It expands, contracts, warps, and eventually rots if not treated with toxic preservatives every year.
Thermowood: The “Best” standard. This wood has been baked in a kiln at high temperatures. The process removes moisture and resin.
Why it wins:
– Stability: It doesn’t shrink or warp, meaning doors won’t jam and gaps won’t appear.
– Rot Resistance: Fungi and insects can’t eat it because the nutrients have been baked out.
– Insulation: Dry wood insulates better.
If your budget allows, always choose a Thermowood model for outdoor use.
Criterion 2: The Heater Brand (Harvia vs. Generic)
The heater is the engine.
Generic Chinese Imports: Often found in cheap “plug and play” kits. Parts are hard to find, and safety certifications can be dubious.
Harvia / Tylo / Narvi: These are the Finnish and Swedish giants. A sauna with a Harvia heater is the industry standard for “Best.”
Why it wins: Reliability. You can buy spare heating elements easily. They heat up faster, hold stones better, and have precise safety cut-offs. Never compromise on the heater brand.
Criterion 3: Wall Thickness
Insulation dictates running costs.
Thin Walls (28-38mm): Common in summer houses marketed as saunas. These will struggle to reach 90°C in winter and will cost a fortune in electricity to run.
Thick Walls (42-58mm+): The “Best” barrel saunas use staves that are at least 42mm thick. Solid log cabins should be 58mm or have added insulation layers. Mass equals heat retention.
Criterion 4: The Roof Solution
Wood is not a roof.
A barrel sauna that shows bare wood on top looks pretty in photos but is a disaster in reality. Water will pool on the top curve and seep in.
The Best Solution: Bitumen shingles (tiles) or EPDM rubber roofing. The “Best” sauna comes with a roofing kit included and pre-cut to size. It protects the timber from UV rain, doubling the lifespan of the structure.
Criterion 5: The Glass Door
Wooden doors warp. In a humid sauna environment, a wooden door will eventually expand and stick, trapping you in or refusing to close.
The Best Solution: Toughened safety glass doors with magnetic catches. Glass doesn’t warp. It ensures a perfect seal every time and lets light in, reducing claustrophobia. Look for high-quality hinges (Abloy or similar) that don’t rust.
Häufig gestellte Fragen (FAQ)
Is Cedar better than Thermowood?
Red Cedar is the ultimate premium wood. It smells incredible and is naturally rot-resistant. However, it is significantly more expensive than Thermowood. Thermowood offers similar durability at a better price point.
What is the best shape?
For efficiency, the Barrel is best (fast heating). For space and headroom, the Cube or Cabin is best. Choose based on usage, not just looks.
Do I need a floor drain?
Ideally, yes. A floor drain makes cleaning easier. If not, ensure the floor slats are removable so you can clean the base underneath.
Conclusion
The “Best” outdoor sauna is one made of Thermowood, heated by a Harvia stove, with walls over 40mm thick and a proper roof. Don’t be swayed by cheap deals on thin-walled spruce sheds. Invest in these core quality markers, and you will have a spa that performs beautifully for decades.