Sauna
Carbon Smart Saunas are designed and built exclusively by Finnish Sauna Builders, one of the largest custom sauna makers in the U.S., with installs across private residences, wellness facilities, and hospitality. The material is Carbon Smart Wood: thermally modified American poplar, salvaged and milled domestically. No import risk, no tariff exposure, and provenance worth putting in the spec.
Introducing Carbon Smart Sauna™
Thermal Poplar, Made for Sauna
Our recommended sauna species: yellow poplar, thermally modified into a lightweight hardwood that's lower in moisture, richer in tone, and dimensionally stable in the high-heat, high-humidity environment of a sauna.
Performance for Commercial Use
High heat, daily use, and aggressive cleaning cycles are where traditional sauna woods warp, split, and drift in color. Thermal Poplar holds its structure and tone, which is why our first flagship installs are commercial.
Chemical-Free
Thermal modification is exactly what it sounds like: wood baked in oxygen-controlled kilns. No preservatives, no glues, nothing to off-gas in a 180-degree room. It's the same process Finnish saunas have relied on for decades.
Lead Times Measured in Weeks
Domestic material means 2–4 week lead times you can actually build a schedule around. When the sauna spec arrives late — and it usually does — the material won't be the thing holding up the install.
We’re here to help
The right material makes all the difference. From choosing products to delivery and installation and every step in between, we’re here to help.
Frequently asked
What is a Carbon Smart Sauna™?
A sauna built with Carbon Smart Wood, Cambium's flagship line of salvaged, U.S.-made lumber, and manufactured by Finnish Sauna Builders. Cambium supplies and stands behind the material; FSB designs, builds, and installs the sauna. Together we're building the next generation of American sauna: domestic material, chemical-free modification, and a story that starts with the tree.
Why Thermal Poplar instead of cedar?
Cedar became the American default decades ago because it was available, soft, and aromatic. But it varies in color from board to board, and it struggles under the demands of modern use — especially in commercial settings. Thermal Poplar delivers deep, consistent tone, greater dimensional stability, and durability suited to high-use environments, from salvaged American hardwood rather than harvested softwood.
Does "thermally modified" mean chemicals?
No — and it's the most common misconception we hear. Thermal modification uses heat, steam, and time in oxygen-controlled kilns. The process removes the sugars that feed mold, stabilizes the cell structure so the wood resists warping, and locks in the dark color through the full thickness of the board. Nothing is added at any stage. If you've sat in a sauna in Scandinavia recently, you've likely sat on thermally modified wood.
How does it perform in commercial settings?
This is where Thermal Poplar's advantages are clearest. Commercial saunas see many times the use of residential ones, plus frequent cleaning — conditions where traditional sauna woods fail early. Thermal modification produces a board that resists moisture movement, holds its color, and stands up to sustained daily heat cycles. Our first commercial flagship, at Aìre Chicago, is establishing the architectural spec for future commercial and hospitality projects.
Where does the wood come from?
Salvaged American trees — brought down by disease, decay, disaster, or development — that would otherwise have gone to waste. Poplar is one of the most common urban trees in America, which is part of why it anchors this line. Every board is milled and thermally modified domestically, so the material in your sauna has a provenance you can actually trace back to a tree.
Can I specify Carbon Smart Wood for a sauna project?
Yes. We work with architects, designers, and GCs on residential and commercial sauna specifications, with spec sheets, samples, and technical documentation available below. Because saunas are often specified late ("sauna by others"), we recommend getting the material conversation started early — our team can support sizing, species selection, and coordination with Finnish Sauna Builders' design team on a 2–4 week material lead time.
Are other species available?
Thermal Poplar is our recommended sauna species, but the full Carbon Smart Wood portfolio — including Cedar, Thermal Oak, and WalNOT — can be prepared for sauna use at the right moisture content. The same material can carry beyond the hot room into benches, cladding, decking, and millwork, so the whole space reads as one continuous palette.
How do I get started?
Request a consultation below. Finnish Sauna Builders' design team will walk through sizing, heater specs, ventilation, installation, and delivery, and you'll come away with a full written spec. Prefer to start with the material? Request a sample and we'll get Thermal Poplar in your hands first.
Ready to build your sauna?
Every sauna is different: the space, the heat, the way you'll use it. Tell us about the project and we'll connect you with Finnish Sauna Builders' design team for a full consultation and written spec.
