Thermally modified sauna wood

Resin-free wall, ceiling and bench boards for saunas in thermally modified Ayous, Ash and Pine. 100% chemical-free, made in the USA.

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Thermally modified wood
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Resin-free, chemical-free wood for the hottest room in the house.

A sauna cycles between dry heat and steam every session. Thermally modified wood has already been through far harsher heat, so it stays stable, sheds moisture and releases no resin or chemicals into the room.

sauna

Resin-free

No sap bleeding at sauna temperatures.

Cool to the touch

Ayous has very low thermal conductivity.

Stable in steam

Boards stay flat through heat cycles.

Chemical-free

Heat and steam only, nothing to off-gas.
Why specify thermowood saunas

Sauna wood that has already survived the heat

Heat-and-steam modification removes the resins and sugars that bleed and darken in ordinary sauna timber, and lowers the wood equilibrium moisture so boards stay flat through repeated heat and steam. Protection comes from the process itself, not preservatives, so the sauna air stays clean.

3 sauna species

Ayous, Ash and Pine, all thermally modified.

Resin-free

Nothing bleeds or smells at temperature.

Low conductivity

Ayous benches stay cool to the touch.

Milled to order

Wall boards, ceiling boards and bench slats.

Profiles, species

Walls, ceilings and benches

Tongue-and-groove wall and ceiling boards and solid bench slats, milled to order. Ayous for benches and backrests, Ash for a richer tone, Pine for a budget-friendly build.

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Thermal-Infused Modern Sauna project (ThermoWood Millworks)

Ayous

Pale, light and cool to the touch, the classic sauna bench wood.
Thermal-Infused Modern Sauna project (ThermoWood Millworks)

Ash

A deeper warm tone and pronounced grain for feature walls.

Heat and steam only, no chemicals, made in the USA

Thermal modification uses only heat and steam. Our thermowood is sourced from certified renewable forests and milled in the USA; the boards are 100% natural, fully recyclable and can go to bio-energy at end of life.

Cool to touch

Thermally modified Ayous

Ayous (obeche) is lightweight with very low thermal conductivity, so benches stay comfortable to sit on. Resin-free after modification.

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thermally modified Ash decking (ThermoWood Millworks)
thermally modified Ayous sauna (ThermoWood Millworks)
Warm tone

Thermally modified Ash

Ash gives a rich brown interior with an open grain; heat-and-steam treated with no chemicals.

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Budget friendly

Thermally modified Pine

Pine gives a warm, even tone at an accessible price, resin-free and chemical-free after modification.

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thermally modified Radiata Pine cladding (ThermoWood Millworks)
thermally modified Ayous sauna (ThermoWood Millworks)
Ayous sauna

Cool to the touch

thermally modified Ash decking (ThermoWood Millworks)
Ash sauna

Warm tone

thermally modified Radiata Pine cladding (ThermoWood Millworks)
Pine sauna

Budget friendly

Western Red Cedar cladding (ThermoWood Millworks)
Western Red Cedar

Aromatic, natural oils

Species

Ayous, Ash, Pine

Resin

None

Chemicals

None

Made in

USA

Sauna questions

Common questions

Installation guides for cladding, decking and porch flooring are on our guides page.

It is resin-free and chemical-free, stays dimensionally stable through heat and steam, and resists decay without preservatives.

Ayous. It is light and has very low thermal conductivity, so it stays cool enough to sit on.

We supply wall boards, ceiling boards and bench slats milled to your layout; send drawings for a quote.

Yes. A fire-retardant treatment backed by ASTM and ULC test reports is available; classification depends on species, profile and application.

Yes, we ship worldwide. Orders go by freight across the US and overseas, with weekly truck delivery across Los Angeles, Orange County and San Diego.

Download the install guides

Install guides