Enduring, rich, and thermally-modified: Introducing Timberline's Thermory Ash Timber Cladding

Written by

07 August 2025

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3 min read

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Crafted for longevity and architectural beauty, Thermory Ash offers a sustainable timber cladding solution that’s dimensionally stable, naturally striking, and perfectly suited to New Zealand’s unique climate conditions.

Known for their durable, FSC-certified timber, Timberline’s solutions are found in architectural projects across the country – used in both interior and exterior applications to deliver natural warmth, textural interest, and long-term performance. 

Rich and chocolatey in tone, Thermory Ash Timber Cladding has been a recent favourite for projects up and down the country.

A unique, durable, and stable alternative to traditional cedar cladding, the material has been thermally modified through a high-head, chemical-free process, resulting in a deep brown colour throughout the full thickness of the timber. This beautiful colour can be preserved with a quality penetrating oil, stained darker with a tinted oil, or left to age naturally and patina to a stunning platinum grey. 

The thermal modification process imparts a beautifully deep shade that brings out the wood's natural grain and character.

What is thermal modification?

A natural way of enhancing wood, this chemical-free heat treatment ensures the wood is extremely durable, stable, and resistant to rot for both indoor and outdoor use. Unlike chemical treatment, Thermory’s thermal modification enhances the wood throughout – not just the outer surface. This thermal modification process uses only heat and steam, with computer-controlled kilns precisely adjusting time and temperature to transform the timber’s internal structure.

At the end of the process, the resulting product is significantly more dimensionally stable, with a lower equilibrium moisture content. This means the timber is less prone to warping, bowing, cupping, twisting or shrinking – making it an ideal solution for external cladding, soffits, and decking in high-exposure environments such as coastal zones or alpine conditions. 

The process also gives the wood a beautifully deep shade that brings out its natural grain and character.

Key features: 

  • Rot-resistant: Every fibre of the board is naturally enhanced with just heat and steam.
  • Exceptional durability: Rot-resistance that few products, exotic or chemically engineered, come close to equalling.
  • Stands up to moisture: A timber cladding that offers significantly reduced absorbency.

A showcase of Thermory Ash Timber Cladding

Wrapped in vertical Thermory Ash Cladding, this Somerfield home is the work of Bob Burnett Architecture and Dan Saunders Construction – designed and constructed with meticulous attention to detail and a focus on energy efficiency and high-performance materials. Replacing the site’s original dwelling, the new building combines sustainability design, thermal efficiency, and modern aesthetics in a compact footprint. 

The residential project, designed by Bob Burnett Architecture and built by Dan Saunders Construction, celebrates the natural beauty of timber.

Each piece of cladding showcases its natural grain and tonal variation, enhanced with Dryden WoodOil in Walnut and elegantly complemented by the home’s dark roof and joinery. This finish deepens the richness of the timber while providing added protection. 

“Our stock profile for Thermory Ash Cladding is a bevelled shiplap,” shares Timberline’s David Dewhurst. Of course, other profiles are available on request as well, and the cladding can be used both vertically and horizontally.”

Dryden WoodOil in Walnut enhances the cladding's natural grain and tonal variation.

Learn more about Thermory Ash Timber Cladding, available from Timberline.