Thermowood Ayous Cladding Board – Triple Slatted Profile – 2450 mm (8 ft.)

Thermowood Triple Slatted Cladding Board

Thermowood is what happens when you take softwood and engineer it into a Class 1 durable timber — without using a single chemical preservative. The thermal modification process — heating timber to 180–215°C in a low-oxygen environment — permanently changes the wood’s cellular structure, dramatically reducing its ability to absorb moisture and making it naturally resistant to rot, insects, and fungal decay. The result is a softwood that performs like a tropical hardwood, with a uniform rich brown colour that runs through the entire board. Stocked in our yard for delivery across Ireland.

Why Thermowood?

Thermowood earns its reputation honestly. Class 1 durability with a service life of 25 years and beyond — entirely natural, entirely sustainable, with no chemical treatments leaching into the environment. The thermal modification gives the timber exceptional dimensional stability: very little movement with seasonal humidity changes, which means tighter tolerances, fewer call-backs, and a facade that stays looking right. The deep, uniform brown colour is consistent throughout the board, so cut ends and chamfers don’t reveal pale wood underneath. Thermowood is the species specified when a project wants tropical-hardwood performance with European softwood credentials.

Installation guidance

Thermowood is straightforward to install for any competent contractor — though the modification process makes the timber slightly more brittle than untreated softwood. Pre-drill all fixing points to prevent splitting, and use stainless-steel A2 or A4 fixings outdoors. The thermal modification removes much of the resin from the timber, so cutting and finishing is exceptionally clean.

Finishing & maintenance

You have two good options with Thermowood, and there’s no wrong answer. The natural route — leaving the timber untreated to silver gradually — is the lowest-effort path forward and very common in contemporary projects. The preserved route — keeping that rich, deep brown colour — takes a little more attention but rewards you with a facade that holds its character. If you choose to oil, use a UV-protective oil designed for thermally modified timbers (we stock the right ones — ask us if you’re unsure which to pair with your boards). Apply within the first few months of installation and refresh annually for the first couple of years, then every two or three years thereafter.