Thermally modified wood is a mature process with a long technical pedigree, decades of commercial use, and a strong track record in exterior and interior wood applications.
Mature European wood technology.
The process uses elevated temperatures in a low-oxygen environment to permanently change the chemistry of wood. It reduces the wood’s ability to absorb moisture, improves dimensional stability, increases resistance to decay, and gives the finished product a rich, warm colour that can resemble cedar or some tropical hardwoods. The result is still real wood, but it behaves differently from conventional kiln-dried lumber.
‘Thermal modification gives us a way to turn abundant coastal fibre into high-value products that are sustainable, non-toxic, and economic when compared to synthetic alternatives.’
Thermal modification is not an experiment.
Modern industrial thermal modification was developed in Europe, with Finland playing the central role in its commercialization. The Thermowood® process was developed by VTT Technical Research Centre of Finland in the 1990s, and the International Thermowood® Association (ITWA) was established in 2000 to govern the process, quality rules, and Thermowood® trademark use.
The International Thermowood® Association defines Thermowood® as an industrial-scale thermal modification method in which wood is modified at elevated temperature, in the presence of steam, under atmospheric pressure, without added chemicals.The production numbers show this is not a laboratory curiosity. According to ITWA production statistics, Thermowood® production grew from 18,799 cubic metres in 2001 to 312,267 cubic metres in 2025, with cumulative production from 2001 to 2025 reaching 3,596,161 cubic metres.
A design-forward local collaboration.
Leckie Studio is leading the architectural design, bringing a thoughtful lens to how the cladding relates to the home’s form, proportions, and material palette. Forte Projects is supporting the build, translating design intent into real construction conditions.
Together, the team creates the kind of project environment Western hoped to learn from: design-forward, locally grounded, and technically useful.
This pilot is not only about showcasing a new wood product. It is about understanding how the product behaves in use, how it supports architectural expression, and what architects, builders, and homeowners may need from Western as the material moves toward broader specification.
Source: International Thermowood® Production Statistics 2025
This volume shows a process that has moved from invention, to standardization, to construction market acceptance. Thermally modified wood has been used across Europe for cladding, decking, terraces, interiors, saunas, landscaping, and exterior architectural applications. It has also been exported into multiple international markets, including North America, where architects and builders are increasingly looking for natural, durable, lower-chemical alternatives to conventional treated wood, tropical hardwoods, and synthetic products.
Europe already proved it works.
The value of the European experience is not simply that Europe used thermally modified wood first. It is that European manufacturers spent decades proving the process at scale, building standards, learning how different species respond, documenting performance, developing installation guidance, and building market confidence with architects, builders, and distributors.
The ThermoWood® process is one of the most established industrial thermal modification systems in use today, developed in Finland and standardized through decades of applied research and commercial production. It is widely recognized for its consistency, clearly defined process framework, and performance classification system.
Schematic representation of the ThermoWood® treatment schedule, adapted from the ThermoWood® Handbook.
The Thermowood® process consists of three phases: drying the wood down to approximately 0% moisture content, raising the temperature to roughly 180°C to 230°C with steam so the wood chemistry changes permanently, then conditioning the wood back to approximately 4% to 7% moisture content to relieve internal stresses.
That is important for a North American audience. The process is not simply ‘baking wood’. It is controlled wood science, and the details matter. Species, temperature, duration, and moisture content all affect the final product.
‘Thermal modification gives us a way to turn abundant coastal fibre into high-value products that are sustainable, non-toxic, and economic when compared to synthetic alternatives.’
– Sepideh Nourian, Product Developer, Western Forest Products
How thermal modification changes wood.
Wood is naturally hygroscopic, which means it takes on and gives off moisture as surrounding conditions change. That moisture movement is one of the main reasons conventional wood swells, shrinks, cups, twists, checks, and becomes more vulnerable to decay in exterior conditions. Thermal modification changes that relationship with moisture.
During thermal modification, hemicellulose is the first wood component to break down, reducing the wood’s ability to absorb water and lowering the amount of simple sugars that decay organisms use as a food source. Cellulose, which provides most of the wood’s strength, stays mostly intact but becomes more stable and less sensitive to moisture movement. At the same time, lignin, the natural binder within the wood structure, becomes more rigid and stable through chemical changes that help lock the cell wall structure in place.
Wood cell wall structure
Extractives, including oils, resins, and sugars, also partly evaporate during treatment, changing the wood’s smell and surface properties while further reducing nutrients available to insects and decay fungi. Together, these changes make thermally modified wood more dimensionally stable, less moisture-sensitive, and more resistant to decay.
‘In plain language, thermal modification makes the wood less prone to absorb water, less attractive to decay organisms, and more stable in changing weather.’
– Sepideh Nourian, Product Developer, Western Forest Products
Jartek – The leader in thermal modification technology.
Jartek was selected because we’re looking for more than a kiln supplier. We need a technology partner with a proven Thermowood® pedigree, deep process knowledge, and the ability to support the development of a new thermally modified Hem-Fir platform with discipline.
Jartek is a Finnish wood processing technology company and a global leader in thermal modification equipment. They have delivered more than 80 thermal modification chambers and more than 20 boiler plants over the past three decades, with systems delivered around the world. They are an early member of the International Thermowood® Association, the organization that owns the Thermowood® trademark and governs quality standards for certified Thermowood® production.
Jartek brings proven European Thermowood® experience, alignment with an international quality framework, global production credibility, and a collaborative R&D approach. As Western develops thermally modified Hem-Fir from pilot production into a market-ready wood platform, the kiln partner needs to support not only heat and steam but also quality, consistency, documentation, and long-term commercial confidence.
From heat treatment to high-value wood products.
Thermally modified Hem-Fir is a premium Pacific Northwest product that’s underpinned by local fibre, vertical integration, responsible sourcing, regional relevance, and technical credibility. We’re not simply adding another SKU. We are using wood science to align our product strategy with the forest we are growing, the fibre we can supply, and the needs of architects, builders, distributors, and homeowners.
The end product has both functional and aesthetic appeal. It is stable, durable, workable, warm, natural, and design-forward. It can be used in exterior wood siding, decking, cladding, fascia, soffits, trim, and other architectural applications where performance and appearance both matter.
