Information about Co2 ThermoTimber

Our ThermoTimber® is a thermally modified wood produced using completely natural methods—heat and steam. The thermal treatment improves the wood’s properties, opening it up to a wide range of applications.

We supply two types of ThermoTimber® products made from either untreated Redwood, spruce or pine (softwood) and untreated Ayous (hardwood).

Both deliver high performance in any weather condition and will as with all timber types naturally turn a pleasing silver/grey over time, a clear UV oil can be applied to prolong the natural colour of the timber.

Our ThermoTimber® is an environmentally sound alternative to pressure-impregnated wood because no harmful chemicals are used in the production of ThermoTimber®. It is resistant to fungi and rot.

Our ThermoTimber® is a dimensionally stable & durable wood product with improved insulation properties.

Our ThermoTimber® is a very popular choice for exterior cladding, decking, and facades and fencing. Because our ThermoTimber® is resin and pith free, you can easily apply glue, paint, oil finishing or surface treatments like a fire-retardant coating or simply leave it natural. Our ThermoTimber® is also an ideal material for interior panelling, flooring, furniture, and other building components. Due to its excellent properties, ThermoTimber® is also a popular choice for sauna interiors and exterior hot tubs.

• 100% natural processing with no chemical additives, biodegradable and recyclable

• Third-party certification under FSC®, PEFC™ chain or custody or both ensures full traceability of the raw material from sustainably managed forests

• Superior performance outdoors, indoors or in different weather conditions thanks to special thermal treatment

• Possesses high dimensional stability, durability and decay resistance, has colour uniformity and reduced thermal conductivity

• No resin leakage, easy to paint or apply surface treatments

• Low maintenance wood, can remain untreated but will take a stain or paint if required.

Ayous ThermoTimber® Hardwood

Ayous is a tropical hardwood tree native to the forests of Central and West Africa growing to a height of 50m. With the botanical name Triplochiton Scleroxylon, and is sometimes refereed to as African Whitewood, Samba, or Wawa. Sustainable timber and third party certification under FSC®, PEFC™. Reddish-brown colour and it can be stained, painted or left to naturally weather to a silver grey colour. Ayous boards are clear, straight grained, quarter sawn, and essentially knot free

ThermoTimber® Softwood

Pine, spruce or redwood supplied from sustainable managed forests. Third party certification under FSC®, PEFC™ are used to monitor and maintain the sustainability of timber used.

ThermoTimber® Specifications

Applications:- External and internal cladding and decking - Fencing

Heat treatment classes:- Two standard thermal modification classes – Thermo-D and Thermo-S.

Durability:- Thermo-D is falling into durability class 2 (EN 350).

Resistance to rot:- Without additional treatments ThermoTimber® by is not resistant to termites.

Dimensional stability:- The thermal treatment process greatly reduces wood’s tendencies to warp, swell or shrink in different humidity conditions. The wood’s equilibrium moisture balance may be decreased to less than 40–50 % compared to untreated timber.

Thermal properties:- 0,09 W/(m K) according EN ISO 13787 + EN 12667

Resistance to fire:- D -s2,d0 according SFS-EN 13501-1:2018

Leaching:- As no substances are added during the ThermoTimber® process, no chemical leaching will occur. In addition, as the resin is removed during the process, the problem of resin leakage through the knots or pitch pockets is removed.

Ecological and safe:- ThermoTimber® is produced using high temperature and steam. Since no chemicals are added during the process ThermoTimber® contains only renewable substances. Disposal of offcuts can be burned or given into the normal waste system.


When selecting your timber type for your project it is worth taking in to consideration BS EN 350 timber durability class.

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.

BS EN 350 has 5 classes of durability they are:-
Class 1 to 3 can be left as untreated timber, a natural ageing process will accrue e.g. most timbers will turn a grey colour. Class 4 and 5 will need to be treated with preservatives.

For further information see