Cedar, thermowood and spruce, without the marketing

Cedar: the traditional premium

Cedar earned its sauna reputation on two properties: natural decay resistance and dimensional stability through wet and dry cycles. Western red cedar is the darker, more aromatic wood of sauna photography. Eastern white cedar is lighter in colour and weathers toward silver. Both cost more than the softwood alternatives because the stock itself costs more.

In our database, 5 models state cedar as their build wood, with published prices from $5.7k to $7.7k. One detail worth pausing on: a seller writing cedar on a photo caption is not the same claim as a spec sheet naming the species. Where a page shows lumber trade names but never the species, we leave the field empty, and the cedar page lists only the models whose sellers commit to the word.

Thermowood: a process wearing a wood's name

Thermal modification bakes lumber in a controlled kiln until its sugars and moisture behaviour change. The result is darker, lighter in weight, less prone to swelling and less appetising to rot. It is sold under names like thermowood, thermally modified timber or heat-treated lumber, and the species underneath varies by maker. The thermowood models in our own database are thermally modified hemlock, per their seller's lumber documentation, which is exactly the follow-up detail the trade name usually hides.

The honest way to read a thermowood listing is as two separate claims: a species and a treatment. Ask for both. The treatment is real and useful outdoors. It is also a reason a spruce or hemlock building can price near cedar, so knowing what you are comparing keeps the premium honest.

Spruce and the budget end

Spruce and pine are the Nordic default for sauna structures, plentiful and easy to machine, and untreated they weather faster than cedar outdoors. Makers manage that with thicker walls, treatments and exterior finishes. The spruce models we track run $4.9k to $5.9k, which in our data sits below the cedar spread. A well-built spruce sauna is not a lesser sauna. It is a different maintenance bargain, and the seller's own care page for the model is the document that defines it.

Hemlock deserves a line of its own because it shows up both bare and thermally modified. It is a pale, straight-grained wood with little scent, which some buyers prefer, and in treated form it is the base of the thermowood models above.

How to use this in a purchase

• Pin the species in writing. If the listing says thermowood or a trade name, ask which species was treated. If the listing shows only photos and adjectives, treat that as your answer about how the seller documents things.
• Price the maintenance along with the crate. The cheaper wood often carries the larger care commitment. The maker's care instructions are part of the price and worth reading before checkout rather than after the first winter.
• Interior claims are separate. Some models pair one wood outside with another on benches and interior walls. The record for each model carries what its seller states, and a dash where it states nothing.

What the sellers state, counted

• 5 of 15 tracked models state white cedar
• 2 of 15 tracked models state hemlock
• 2 of 15 tracked models state spruce
• 1 of 15 tracked models state pine
• 5 of 15 state no species at all

Counts are computed from the database at build time and change as records are added.