How Thermally Modified Wood Is Redefining Architectural Design With Sustainable Materials | Advertorial

Seeking durable, sustainable, and beautiful materials, architects are increasingly turning to thermally modified wood.

Material choices are rarely black and white in contemporary architecture. Sometimes, regular wood suffices when designs include traditional roof overhangs that shield exterior walls from the elements. But today’s buildings often favor sleek lines and exposed surfaces, leaving materials vulnerable to weathering. In these cases, thermally modified wood (TMW) is becoming an increasingly popular choice.

This shift is about performance, client expectations, aesthetic preferences, and sustainability goals. Across North America, in particular, architects are under pressure to deliver buildings that combine strong design with measurable environmental responsibility. As such, TMW is gaining attention as a material that meets these demands, offering durability, visual appeal, and a lower ecological footprint.

ARCHITECTURE AND AESTHETICS
Architect Mari Hunt, whose practice frequently centers around wooden structures, explains that her interest in TMW has always been rooted in the architecture itself, such as how a structure connects with its surroundings and reflects the client’s vision. “The material supports that vision beautifully.”

Hunt’s micro hotel Kaseke in Estonia’s Maidla Nature Resort is a striking example of TMW’s versatility. From terraces and façades to the roof and interior surfaces, the cozy cabin is entirely clad in thermally modified wood. “I wanted to use the same material throughout the building. TMW was the only choice to achieve the aesthetic of a unified material that feels both durable and soft for visitors.” According to Hunt, other materials, such as stone, glass, or plastic, don’t offer the same flexibility or natural warmth as wood.

From residential homes to commercial buildings, TMW is being used in a wide range of projects. Hunt recently designed an eco-hotel in Spain, mainly using thermally modified wood. “Given the intense sun exposure there, we chose TMW because it weathers beautifully, turning gray over time, which we thought would look great.”

She adds, “Thermal pine is the most common thermally modified wood that I work with. We often use it as a more affordable option for terraces. For interior design, especially in saunas, we use thermally modified deciduous trees.”

STANDARDS AND SUSTAINABILITY
While architects like Hunt approach thermally modified wood as a means to support architectural vision and harmony with surroundings, manufacturers see growing interest from designers who are also drawn to the material’s environmental credentials. Jason Martell, Project Manager at Thermalwood Canada, notes that profiled thermally modified wood “looks stunning,” and that many architects are choosing it as a responsible alternative to exotic woods sourced from rainforests and other environmentally compromised regions.

“Once architects use thermally modified wood in a project, they keep coming back,” says Martell. “They hear the positive feedback and see the results. Architects want a reliable, predictable product that delivers durability, stability, and aesthetics – and TMW has proven time and again to be a great fit.”

The sustainability story behind TMW is compelling. Thermalwood Canada uses clean-burning propane to power its kilns, and the modification process relies solely on heat and steam. “We source almost all of our wood from Quebec,” says Martell. “Some modifiers ship wood overseas for treatment and back again, which makes net-zero emissions projects difficult for architects to achieve.” A local-first approach aligns well with certifications like LEED and WELL, which reward projects for using low-emission, responsibly sourced materials.

Consistency and quality control are also essential for architects working on high-profile or long-lasting projects. To ensure reliability across applications, thermally modified wood produced under the Thermo-Wood® trademark follows strict guidelines developed by the International ThermoWood Association (ITWA). These standards include a recipe-based approach, where each wood species is treated using a specific combination of temperature, time, and steam conditions.

This process permanently alters the wood’s chemical structure, improving its durability, dimensional stability, and long-term resistance to rot, decay, parasites, and harsh climates. “We have a 25-year warranty on our decking and a 60-year warranty on our cladding,”

Martell explains. “Architects also appreciate its better fire rating compared to rough lumber.”
The ITWA also enforces an audited quality control system, meaning only certified producers can use the ThermoWood® name and quality logo. This makes sure that architects and designers can trust the material’s performance and consistency across projects.

PRECISION AND PERFORMANCE
Despite its growing popularity, TMW still faces misconceptions, particularly around cost and implementation. “Architects sometimes think it will be over budget,” says Martell. “But because we use species like Canadian Ash consistently, we’ve been able to deliver a high-quality product at a great price.”

Another issue arises during construction. “Architects assume that because they specified TMW, it will be used. But we often see contractors pivot to a lower-grade product to cut costs, despite what was chosen,” he adds.
Looking ahead, the future for TMW in North America seems bright. Consumption reached over 850,000 cubic meters in 2024, driven by the U.S. and Canada’s booming housing sector and rising interest in sustainable construction. In fact, TMW decking sales grew by 22% year-over-year in 2022, and a 2023 survey found that 32% of North American architects now specify TMW for moisture-prone areas, up from 18% in 2020.

The rise of thermally modified wood reflects a broader shift in the lumber industry toward trust, precision, and sustainability. Manufacturers are delivering customized, high-performance products and supporting architects throughout a project’s lifecycle, which is a testament to their dedication to meeting the evolving demands of modern construction.

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By ASA BUTCHER