The Best Timber for a Sauna: A Complete Guide to Sauna Woods

The choice of timber is one of the most important decisions in any sauna project. Here is a complete guide to the most popular sauna woods — comparing performance, aesthetics, and cost.

The timber you choose for your sauna will define its aesthetic, performance, and longevity. Not all woods are suitable for the sauna environment — the combination of high heat, humidity, and repeated thermal cycling demands specific properties. Here is a guide to the timbers we work with most frequently.

Western Red Cedar

Western Red Cedar is the most popular choice for both interior lining and exterior cladding of saunas, and for good reason. It is naturally aromatic — releasing a warm, distinctive scent when heated. It is highly resistant to moisture, decay, and insects. It is dimensionally stable, meaning it moves very little with changes in heat and humidity. And it ages beautifully, developing a silver-grey patina over time.

The main consideration with Cedar is that it is a relatively soft wood — it can be susceptible to denting and marking with heavy use. For bench surfaces, we often recommend a harder timber such as Alder or Abachi.

Clear Alder

Alder is the traditional Finnish choice for sauna benches and is one of our most popular interior lining timbers. It is a light, fine-grained hardwood with a warm, pale tone. It has excellent thermal properties — it does not get uncomfortably hot to the touch even at high temperatures, making it ideal for bench surfaces. It is also hypoallergenic and does not release resins when heated.

Thermowood

Thermowood is pine or spruce that has been heat-treated at temperatures of 185–215°C to permanently alter its cellular structure. The result is a timber with dramatically improved stability, moisture resistance, and durability — comparable to tropical hardwoods, but produced from sustainably managed European forests.

Thermowood has a distinctive rich, dark brown colour that deepens over time. It is an excellent choice for both interior lining and exterior cladding, and is particularly well-suited to outdoor saunas in the British climate.

Thermo Spruce

Thermo Spruce is heat-treated spruce — similar to Thermowood but with a slightly lighter, more golden tone. It offers excellent stability and moisture resistance, and is one of our most popular choices for interior lining. It has a clean, contemporary aesthetic that works well in modern sauna designs.

Larch

Larch is an excellent choice for exterior cladding on outdoor saunas. It is one of the most durable European softwoods, with natural oils that provide good resistance to moisture and decay. It has a warm, golden tone when new and weathers to a beautiful silver-grey over time. Larch is also sustainably sourced and widely available in the UK.

Abachi

Abachi (also known as Obeche) is a light African hardwood that is increasingly popular for sauna benches. It has excellent thermal properties — it remains cool to the touch even at high temperatures — and is very smooth and splinter-free. It is a good alternative to Alder for bench surfaces.

Our Recommendation

For most indoor saunas, we recommend Clear Alder for the interior lining and bench surfaces — it is the traditional Finnish choice and performs exceptionally well. For outdoor saunas, we typically recommend Thermowood or Larch for the exterior cladding, with Cedar or Alder for the interior. The best choice for your project will depend on your aesthetic preferences, budget, and the specific environment.