Supporting Our Woodlands: Sustainable British Timber

As part of our ongoing commitment to sustainability and quality, over the last few years Heartwood Saunas has transitioned from using Canadian cedar to locally sourced thermally-modified British wood species for our saunas' interiors as standard. This change reflects both our dedication to environmental responsibility, as well as to durability, strength and quality in sauna construction. In this video, we explore the fascinating world of thermally modified timber alongside industry expert Tom Barnes, as we uncover its remarkable benefits and discuss the pivotal role the construction industry plays in supporting British woodlands.

Why the Switch?

Although we use Welsh western red cedar for our external cladding, the premium knot-free cedar we previously used for our internal cladding and shingles came from mature forests in Canada that are hundreds, if not thousands of years old. This means that the trees' growth rings are closer together, producing exceptionally strong timber, ideal for withstanding the heat of a sauna. However, it also means that it takes hundreds of years to regrow these forests, and although they are certified as sustainable, as efforts are being made to regenerate the forest and preserve the invaluable wildlife habitat, the bottom line is that it is unavoidable that using these trees contributes to the destruction of rare ancient forests. This, as well as the carbon footprint of transporting the timber from Canada to the UK, has motivated us to seek more local, sustainable options that do not compromise on the durability and strength needed for quality sauna building.

Thermally Modified Timber

Native British heat-treated woods are local fast-growing hardwoods transformed by thermal modification, a chemical-free process that reconfigures the cell structure of the wood by superheating it to 210°C. This natural method removes moisture, resin and other extractives, resulting in an extremely stable and durable rot-resistant material, ideal for standing up to the heat, water and steam of a sauna and certified to withstand the elements for 30 years. Thermally modified woods were first developed specifically for use in saunas in Northern Europe and are widely regarded as one of the best timbers for use in sauna building. Using local thermally modified wood reduces our dependence on old growth timber and its associated negative ecological impacts, and increases the demand for UK timber, supporting the regeneration of our local forests.