Arbor Wood Co.

ThermoWood® is a registered classification for timber that's been thermally modified to a defined standard, using only heat and steam — no chemicals. It's owned by the International ThermoWood Association, and only member producers like Arbor Wood can carry it. The modification works at the cellular level, breaking down the sugars and acids that feed rot and insects and reducing how much water the wood absorbs — for a stable, decay-resistant material with a richer, darker tone all the way through.

Arbor Wood's thermally modified wood is produced in a three-phase kiln process using only heat and steam. The first phase gradually raises the temperature to drive moisture out of the wood. The second applies intense, oxygen-starved heat that restructures the wood's cells — removing the food source for mold, rot, and fungal decay and making the wood hydrophobic, so it absorbs far less water. The final phase reintroduces steam to cool the wood and bring it back to a workable moisture level.

Arbor Wood's materials work in both interior and exterior applications, including cladding, decking, dimensional lumber, soffits, interiors, saunas, and furniture. They can stand in for tropical hardwoods, chemically treated lumber, and composites. One caveat: thermally modified wood isn't intended for structural use, so standard framing lumber should still carry load-bearing elements.

No finish is required. Left untreated, the wood weathers to a natural silver-gray patina and is expected to last 25+ years without serious degradation, warping, or buckling. If holding the original color matters, a penetrating UV oil (Arbor Wood recommends CUTEK® Extreme) can be applied and reapplied as needed; color longevity depends on factors like species, exposure, and surface prep.

Yes. The process uses heat and steam rather than harsh chemicals, so there's nothing that can leach out over time. The timber is domestically grown and responsibly harvested under sound forest-stewardship practices, keeping the footprint low from sourcing through production.

Because the process works across a range of species, there's usually an option to fit most budgets. Compared with composites, exotic hardwoods, and premium softwoods, Arbor Wood is competitively priced and because it's made in the USA, it carries a lower carbon footprint than imported exotic alternatives.