Treating thermally modified timber

Thermal modification gives dimensional stability and decay resistance — but no UV protection. Untreated thermowood greys quickly and unevenly. SiOO:X controls the surface without closing the fibre.

THE ORIGINAL SILICATE WOOD PROTECTION SINCE 1994

What thermal modification does — and does not do

Stable but UV-sensitive

Thermal modification reduces moisture movement but does not protect the surface against solar degradation.

The brown tone fades

Untreated thermowood loses its warm tone within a couple of seasons and greys unevenly.

More brittle fibre

Thermally modified timber is more brittle. A system that needs no sanding or scraping protects the surface.

Treating thermowood

Thermowood often absorbs quickly at the surface but less deeply — apply evenly and avoid pooling.

Coverage on thermally modified timber

Expect 8–10 m²/litre for Wood Protector, with local variation depending on modification level and planing. The calculator returns exact volumes based on your dimensions and coat count.

Frequently asked questions about thermowood

Does thermowood need treating?

For dimensional stability, no. To control appearance and slow UV degradation of the surface fibre, yes.

Can I keep the brown tone?

Treatment slows the change, but all exterior timber patinates over time. Premium Color can be used on cladding to steer the shade.

Is the application schedule the same?

Yes — 2+1 on cladding and façades, 1+1 on decking.

Does it work on Thermory, Lunawood and similar?

Yes, the system works on thermally modified timber regardless of supplier.