Appearance and Aesthetic Appeal

Both Iroko and Thermo-Ash bring a warm, natural look to outdoor spaces, but they have distinct visual characteristics:

• Iroko Decking: A tropical hardwood with golden-brown to rich bronze tones that deepen over time. Its interlocked grain adds natural character, making it a timeless choice for traditional and contemporary gardens alike.
• Thermo-Ash Decking: A thermally modified European hardwood with a rich, dark chocolate colour that provides a modern, sleek finish. Over time, it naturally weathers to a beautiful silver-grey if left untreated.

Durability and Stability

Your decking needs to withstand the UK’s unpredictable weather – from heavy rain to frost and sunshine.

• Iroko: Naturally durable and resistant to rot, decay, and harmful insects. It can last 25 - 40 years with proper care. The timber is also kiln-dried making more stable and suitable for various applications.
• Thermo-Ash: Modified through heat and steam treatment, improving its dimensional stability and making it highly resistant to warping, swelling, or splitting. Expected lifespan is 25+ years with low maintenance.

Both options are hardwearing and suited to high-traffic areas, but Thermo Ash has an edge in stability, making it less prone to movement over time.

Environmental Sustainability

If eco-friendly decking is a priority, Thermo-Ash is one of the most sustainable hardwood choices on the market.

• Thermo-Ash: Made from European ash timber, heat-treated without chemicals, and sourced from FSC-certified forests. A very low environmental impact.
• Iroko: A tropical hardwood sourced from Africa so the transportation distance can increase its carbon footprint compared to European timbers.

Thermo-Ash is the greenest choice, ideal for environmentally conscious projects.

Maintenance and Finishing

• Iroko: Benefits from regular oiling to maintain its rich colour and protect the surface from weathering. Without treatment, it gradually silvers over time.
• Thermo-Ash: The brilliant thing about our Thermo-Ash stock is it comes pre-oiled with UV protection, so it’s weather-ready on installation and needs minimal upkeep to preserve its colour.

Both timbers are low maintenance with the option to treat if you want to protect its original colouring, but Thermo-Ash has the upper hand here since it comes pre-oiled with UV protection.

Price and Availability

• Iroko: Generally mid-range in cost, at a much more affordable price than luxury choices like Ipe.
• Thermo-Ash: Priced at the more premium end of the market while availability is increasing as demand for sustainable decking grows.

Your choice will depend on budget vs sustainability priorities.

Workability

• Thermo-Ash: These boards are end-matched which makes installation a lot faster and more efficient, which can reduce wastage and labour time.
• Iroko: The multi-directional grain can cause challenges during the procurement process or when machined, so we generally recommend factoring in 15% wastage to your order.

Which Should You Choose?

Both timbers are exceptional choices, offering natural beauty, durability, and a long lifespan. The decision often comes down to personal style, environmental impact, and budget.

At Southgate Timber, we supply a wide range of high-quality hardwood decking boards, including Iroko and Thermo-Ash, available for fast UK delivery. Our team can guide you through the options to help you choose the perfect material for your garden project. Browse our decking range online or contact us today for expert recommendations.