What Is Thermo-Ash Cladding

Thermo-Ash is a thermally modified hardwood, produced by heating ash timber to high temperatures in a controlled environment. This process improves durability and reduces movement, making it well suited to external use. Thermo-Ash is often chosen for:

• Its rich, dark tones
• Smooth, consistent finish
• Premium appearance
• Strong stability
• It comes pre-oiled, helping reduce preparation time and ongoing maintenance.

Common profiles include:

• Thermo-Ash 20 x 132mm Cladding C34
• Thermo-Ash 20 x 132mm Cladding C6

What Is Thermo Ayous Cladding

Thermo Ayous is a thermally modified lightweight timber that offers excellent stability and ease of installation. Its widely used across modern garden rooms and exterior cladding projects due to its clean appearance and practicality. Thermo Ayous is known for:

• Its light weight
• Smooth, uniform finish
• Ease of handling and installation
• A slightly cheaper alternative to Western Red Cedar for its similar appearance

Common profiles include:

• Thermo Ayous 20 x 95mm Channel Groove ST65.TA
• Thermo Ayous 20 x 144mm Channel Groove Vertical ST6.TA
• Thermo Ayous 20 x 144mm 3-Stripe
• Thermo Ayous 20 x 95mm T.G.V ST0.TA

Key Differences Between Thermo-Ash and Thermo-Ayous

Appearance

Thermo-Ash has a darker, richer tone with a more premium feel, making it ideal for high-end or contemporary designs.

Thermo Ayous offers a lighter, more neutral appearance, which works well for clean, modern builds such as garden rooms.

Weight and Workability

Thermo Ayous is significantly lighter, making it easier to handle and install, especially on larger projects.

Thermo-Ash is denser and heavier, which contributes to its durability but may require more effort during installation.

Durability and Performance

Both timbers benefit from thermal modification, improving their resistance to moisture and movement.

Thermo-Ash, as a hardwood, offers a more robust and durable option, while Thermo Ayous provides excellent stability with the advantage of being lightweight.

Maintenance

Both options are relatively low maintenance compared to untreated timber.

Thermo-Ash is supplied pre-oiled, which helps protect the timber from the outset and reduces the need for immediate treatment.

Thermo Ayous can also be treated or left to weather naturally depending on the desired finish.

Installation Style

Thermo Ayous cladding is available in a wide range of profiles, including TGV, channel groove and 3-stripe options. Depending on the profile selected, it can be installed either vertically or horizontally.

Thermo-ash cladding is supplied in precision profiles such as the 20 x 132mm C34 designed for vertical installation, and the C6 designed for horizontal installation. The C6 profile system also includes dedicated fixing clips for a clean and consistent installation. In addition, thermo-ash is available in decorative rhombus tiles for feature wall applications.

Sustainability

Both Thermo-Ash and Thermo Ayous are environmentally responsible choices due to the thermal modification process. This treatment uses heat and steam rather than chemicals, improving durability and stability without introducing harmful substances.

Thermo Ayous also benefits from OLB certification, ensuring the timber is sourced from responsibly managed forests.

Where Each Timber Works Best

Other Cladding Options to Consider

Depending on your project, you may also want to explore:

• Western Red Cedar cladding for a natural, lightweight option
• Thermowood Pine cladding for a cost-effective thermally modified alternative

Each option offers a different balance of appearance, durability and budget.

Fixings and Finishing

Whichever timber you choose, using the correct fixings and treatments is essential for long-term performance. This includes:

• Stainless steel fixings
• Hidden fixing systems where appropriate
• Protective oils to maintain colour and finish

Southgate Timber stocks a range of treatment products, including Owatrol and Osmo, suitable Thermo Ayous cladding, while it's recommended to top up Thermo-Ash cladding when needed with the Thermory Oil Dark.

Final Thoughts

Both Thermo-Ash and Thermo Ayous cladding offer excellent performance thanks to thermal modification, but they suit slightly different types of projects. Thermo-Ash is ideal for those looking for a premium, durable finish with minimal maintenance, while Thermo Ayous provides a lightweight, practical and versatile option for modern builds. Choosing between the two ultimately comes down to the look you want to achieve and the requirements of your project.

FAQ’s

Is Thermo-Ash better than Thermo Ayous cladding?

Thermo-Ash is typically chosen for its premium appearance and higher durability as a hardwood, while Thermo Ayous offers a lightweight, more cost-effective alternative that is easier to install. The best option depends on your project priorities, whether that is performance, appearance or ease of installation.

Which cladding lasts longer, Thermo-Ash or Thermo Ayous?

Both benefit from thermal modification, which improves durability and stability. Thermo-Ash, as a hardwood, generally offers a longer lifespan, while Thermo Ayous still provides excellent long-term performance when installed correctly.

Can Thermo-Ash and Thermo Ayous cladding be installed vertically and horizontally?

Yes, both can be installed vertically or horizontally depending on the profile and design preference. Some profiles are more suited to specific orientations, so it is important to check product details before installation.

Does Thermo Ayous cladding need treating?

Thermo Ayous can be left untreated to naturally weather to a silver-grey finish. If you prefer to maintain its original colour, applying a suitable oil or treatment is recommended