This causes chemical and structural changes to occur within the timber. All the moisture and resin are effectively removed from the timber decreasing the likelihood of swelling and cracking compared to non heat treated timber making it a more stable product and longer lasting.
The heating process breaks down hemicellulose so the wood doesn’t contain the nutrients which allow rot and fungi to grow and develop. The process does not involve injecting or spraying any chemical on to the wood.
It is an environmentally friendly product and all our timber originates from well-managed FSC certified forests.
The colour of Thermowood is affected by the temperature the wood is subject to and the length of time it is exposed to the heat. There will be a slight variance in colour due to different softwood densities, but generally, the higher the temperature the wood is exposed to, the darker the Thermotimber.
Thermotimber Maintenance & Treatment
Thermotimber has a 30yr guarantee, because of its high durability it does not need a surface treatment applied to it. You may choose to add a finish, stain or paint to the timber to enrich its colour see our accessories page, but if it’s left untreated, the wood will naturally change to a silvery grey.
Durability is the ability of a species to resist decay either naturally or through preservatives. The Class is based on the ability of the heartwood (inner part of the tree) to resist fungal decay. The sapwood (the living outermost portion of the tree)is considered not durable and should not be used for external projects without preservative.
Class 1 to 3 can be left as untreated timber, a natural ageing process will accrue e.g. Larch will turn a grey colour. Class 4 and 5 will need to be treated with preservatives.
For further information see www.greenspec.co.uk/building-design/cladding-durability-quality