Thermo-ash

Thermo-ash: the warmth of temperate forest wood, the resistance of tropical woods.

Sourced from sustainably managed forests and thermally treated at 215°C without any chemicals, modified ash stands out as an elegant, stable, and responsible alternative for all outdoor installations.

The excellence of thermo-ash

Superior quality wood: Each board is selected for the fineness of its grain and the homogeneity of its surface — a level of excellence visible from installation.
Remarkable dimensional stability: The low moisture absorption of thermally modified wood significantly limits deformations related to climatic variations — shrinkage and swelling are almost non-existent, even in severe exposure.
Certified Durability Class 1: Thermo-ash achieves the highest European classification for natural durability, guaranteeing resistance to rot and biological agents without chemical impregnation.
Fast and clean installation: Compatible with the Grad® system, clip fastening on an aluminum substructure ensures installation without visible screws, a perfectly aligned finish, and hassle-free on-site installation.
100% natural and responsible wood: Thermal treatment uses only heat and steam — no chemicals, no hazardous waste at the end of its life. The ash comes from sustainably managed forests.

Wood Aging

Upon installation, thermo-ash displays a warm and deep caramel brown hue, characteristic of the 215°C thermal treatment. Its fine grain and homogeneous surface give it a distinctive architectural character from the moment it’s installed.

Under the progressive action of UV rays and climatic cycles, the board begins a controlled evolution towards a bright and homogeneous silver-grey. This process starts upon installation and can extend over several months to several years depending on the level of exposure — without ever affecting the material’s performance.

Maintain the initial shade

Annual application of a honey-toned saturator helps maintain the original caramel brown color for as long as possible.

Routine maintenance

Bi-annual cleaning with soapy water and a brush, or with a wood brightener, is sufficient to maintain the surface appearance. Thermo-ash requires no chemical preservation treatment — its durability is acquired through transformation, not application.

Allow to age naturally

To accompany natural greying while protecting the board, the application of a clear base oil is recommended — it allows the wood to evolve towards its silvery patina in a homogeneous and controlled manner.

Upon installation 1 year

Certified Durability

Classified EN 350 Class 1, it resists fungi, insects, and weathering without chemicals.

215°C Treatment

Heated under steam, the wood gains stability and durability: without any chemical additives.

Natural Aesthetics

Fine grain, dark brown hue, carefully sorted surface: a refined finish from installation.

Treatment Process

Thermal modification of wood is a 100% natural process that profoundly transforms the physical and chemical properties of wood without using any chemicals. Developed on an industrial scale in cooperation with VTT, the Technical Research Centre of Finland, the process consists of modifying wood at high temperatures in the presence of water vapor, under atmospheric pressure. The cycle unfolds in three phases: a slow temperature increase in a water vapor atmosphere to prevent cracking and combustion of the wood, a stagnation at approximately 212°C which causes the structural modification of the wood, followed by a gradual cooling accompanied by slight humidification to prevent splitting. At the end of the treatment, the wood’s moisture content drops to about 4 to 6%, and its hygrometric balance is permanently reduced, which gives it remarkable dimensional stability and much better resistance to climatic variations compared to untreated wood. The result is a naturally durable, rot-proof, and stabilized material, usable both indoors and outdoors in all climatic conditions, without requiring additional chemical treatment.