Myth 1: Thermo-Ash isn’t durable outdoors

Truth: Thermo-Ash is exceptionally durable. The thermal modification process changes the structure of the timber, reducing its moisture content and making it highly resistant to decay and insect attack. With proper installation and care, Thermo-Ash decking can easily last 25 years or more, even in the unpredictable British climate.

Myth 2: It warps and moves like normal ash

Truth: Untreated ash can be unstable outdoors, but Thermo-Ash is completely different. The heat-treatment process increases durability and dimensional stability, meaning the boards are far less likely to warp, twist or cup. This makes Thermo-Ash a reliable choice for large decking areas where consistency is essential.

Myth 3: It’s only about looks

Truth: While Thermo-Ash is undeniably beautiful with its rich chocolate-brown tones, it offers much more than aesthetics. It combines the appeal of hardwood with the technical performance of modified timber, with the boards being end-matched to compete with the ease of alternative materials like composite. Stability, durability and sustainability are just as much a part of its value as its stunning appearance.

Myth 4: Thermo-Ash requires too much maintenance

Unlike many decking timbers, our Thermo-Ash stock comes pre-oiled with UV protection, which means you don’t need to treat it upon installation, saving you both time and effort. Over time, all natural timbers will weather, and Thermo-Ash will gradually develop a silver-grey patina if not regularly maintained. This isn’t damage, but a natural process. If you prefer to keep the rich chocolate-brown tones, a simple re-application of UV-protective oil will keep the colour vibrant. Either way, Thermo-Ash requires far less upkeep than many traditional hardwoods.

Myth 5: It isn’t environmentally friendly

Truth: Thermo-Ash is actually a sustainable choice. It's FSC-certified meaning its sourced from responsibly managed forests, and the thermal modification process uses only heat and steam, no harmful chemicals. This makes it a safe, eco-friendly alternative to tropical hardwoods.

Myth 6: Hidden fixings aren’t an option

Truth: At Southgate Timber, we supply Thermo-Ash decking with hidden fixing systems, creating a clean, seamless look without visible screws on the surface. This makes it a versatile option for high-end projects where detail and finish matter most.

Thermo-Ash decking combines beauty, strength, stability, and sustainability in one package. Many of the common myths come from confusing it with untreated ash or misunderstanding the thermal modification process. The truth is, Thermo-Ash is one of the most reliable hardwood decking options available in the UK today.

At Southgate Timber, we’re proud to supply Thermo-Ash decking alongside our full range of premium hardwoods. If you’d like to see the quality for yourself order online or try a sample first!