When we talk about luxury sauna design at Theraluxe, we’re not just talking about what looks good. We’re talking about what feels good, what holds up, what performs beautifully over time and what turns a simple structure into a refined, long-lasting wellness space. And when it comes to materials, few choices are as thoughtful, functional and stunning as thermal wood.
You may have heard the term “thermowood” floating around in sauna design circles. But what exactly is thermal wood? Why are top-tier sauna builders in Canada, like us, leaning into it more than ever? And how does it compare to traditional softwoods like cedar?
Let’s take a closer look at what makes thermal wood such a meaningful upgrade in home and commercial sauna builds and why, at Theraluxe, we believe it’s one of the best decisions you can make for your wellness space.
What is Thermal Wood?
Thermal wood (also called thermally modified wood or thermowood) is natural timber that has been heat-treated at high temperatures, typically between 160°C and 215°C, under controlled conditions. The process involves no chemicals. Just heat, steam and time.
The goal? To alter the wood’s structure at a cellular level, reducing its ability to absorb moisture and improving its durability, stability and resistance to decay.
The result is a beautifully aged-looking timber with a deep, rich tone, enhanced performance and a lower environmental impact compared to chemically treated woods.
In sauna builds, where moisture, heat and longevity are non-negotiables, thermal wood shines.
Why We Love It: Performance Meets Beauty
At Theraluxe, we don’t just build saunas. We craft sanctuaries. That means every element, from the bench slats to the ceiling paneling, is chosen with care. Thermal wood checks every box for us and here’s why.
1. Superior moisture resistance
Traditional softwoods like cedar and spruce can absorb and retain moisture over time, especially in high-humidity environments like a sauna. This increases the risk of warping, swelling or mold formation.
Thermal wood, on the other hand, has undergone a process that drastically reduces its ability to absorb water. It stays dimensionally stable, even after years of heat-ups and cooldowns. That means fewer cracks, less maintenance and a longer-lasting structure.
Example: In outdoor saunas exposed to rain, snow or coastal air, thermowood cladding can resist weathering far better than untreated wood.
2. Naturally antibacterial
The high-heat modification process also destroys nutrients in the wood that bacteria and fungi feed on. This makes thermal wood naturally more hygienic, especially valuable in high-touch zones like benches and backrests.
For wellness spaces, this isn’t just a bonus. It’s a built-in safeguard.
3. Sustainable and chemical-free
Thermal wood is a great option for eco-conscious homeowners. It’s produced using natural processes without any synthetic additives. It often comes from sustainably harvested species like ash, pine or spruce and its enhanced lifespan means fewer replacements over time.
Compared to chemically treated lumber, thermowood is a win for both indoor air quality and environmental impact.
4. Refined aesthetic appeal
Let’s talk about beauty.
Thermal wood carries a rich, warm tone that’s visually striking and naturally sophisticated. The color deepens in the treatment process, bringing out the grain and creating a luxurious, lived-in look, like something aged gracefully.
In practice: We often use thermally modified Spruce or Aspen for modern sauna interiors. The sleek brown hues pair beautifully with black steel, bronze lighting and large-format glass. It reads minimal, but warm. Bold, but grounded.
How Does Thermal Wood Compare to Cedar?
Cedar is timeless for good reason. It’s aromatic, durable and loved for its naturally warm color and familiar scent. At Theraluxe, we still use cedar in many builds, especially for clients who love its traditional look and signature fragrance.
Where thermal wood stands apart is in its modern performance qualities. Its resistance to moisture, dimensional stability and chemical-free treatment make it an excellent option for those looking for longevity, modern aesthetics or who may have sensitivities to strong wood scents.
Rather than replace cedar, thermal wood expands the palette of possibilities for custom sauna design.
Where We Use Thermal Wood in Our Saunas
At Theraluxe, thermal wood isn’t a feature, it’s a foundation.
You’ll find it in key components across several of our signature models:
- Interior walls and ceilings – For rich ambiance and lasting performance
- Benches and backrests – Where comfort, hygiene and temperature management matter most
- Flooring – Durable and naturally splinter-resistant
- Custom heater guards – Where heat proximity requires stable, reliable materials
- Custom shelving and storage – Built to match the aesthetic of the rest of your space
We often pair thermowood interiors with soft LED lighting, seamless glass doors, and black powder-coated steel elements for a sophisticated, immersive feel.
Why It Matters for Cold Climates
In Canadian winters, the performance of your sauna materials gets put to the test.
Thermal wood stands up exceptionally well to freeze-thaw cycles, sudden changes in humidity and constant shifts between hot and cold. Unlike untreated wood, which can shrink, swell or crack, thermal wood holds its shape and beauty season after season.
This makes it ideal for year-round use, whether your sauna sits lakeside, tucked into a forest escape or nestled on a rooftop terrace.
Thermowood in Contemporary Sauna Design
Thermal wood isn’t just a technical upgrade. It’s become a defining element of modern sauna architecture.
Designers are embracing it for its clean lines, uniform tone and versatility. It pairs seamlessly with minimalist interiors, Japandi-inspired palettes, black metal finishes and indoor-outdoor spa concepts.
A few ways we style thermowood in our builds:
- Horizontal slat paneling for a sleek, gallery-like interior
- Shadow-gap joints to highlight material integrity
- Integrated LED backlighting to warm the grain
- Pairing it with stone or concrete for a grounded, elemental look
Thermal wood allows you to embrace modernity without sacrificing tradition and that’s the balance we always aim to strike at Theraluxe.
What to Look For in Quality Thermal Wood
If you’re considering thermal wood for your sauna build, make sure to choose high-quality materials.
Here’s what we recommend:
- Thermally modified Aspen or Magnolia – Premium finishes with exceptional visual and tactile quality
- Grade A or select – Minimal knots for consistency, especially in high-heat environments
- Certified thermal treatment process – Consistency and safety matter
- Responsibly sourced – Look for FSC-certified woods from reputable suppliers
At Theraluxe, we only use thermal wood that meets these standards and we’re proud to support ethical forestry in all our sourcing. Each piece we use is selected not just for how it looks, but for how it performs long-term in real-world settings.
Thermally Modified Woods We Use and Who They’re Perfect For
At Theraluxe, we select our wood with purpose. Every panel, bench and floorboard is more than just material, it’s a decision rooted in performance, comfort and aesthetics. The thermal modification process enhances each species uniquely, making some woods better suited for specific applications and personal preferences.
Let’s take a closer look at the thermally modified woods we use and where they shine:
- Thermally modified spruce
Spruce is a lightweight, softwood with a clean grain and light tone, ideal for creating that classic Scandinavian sauna feel. When thermally modified, it develops a warm golden hue and improved dimensional stability.
It’s a popular choice for paneling and ceilings, offering visual warmth without overpowering the space. Its natural lightness reflects ambient lighting beautifully, creating a serene, airy environment.
Ideal for: Minimalists, lovers of Nordic design, and those who want a bright, calming atmosphere inside their sauna.
- Thermally modified hemlock
Hemlock is known for its durability, subtle grain and knot-free appearance. After thermal treatment, its color deepens to a rich honey or amber, lending an understated luxury to any sauna interior.
It’s smooth to the touch and splinter-resistant, making it an excellent option for areas where skin contact is frequent, like benches and backrests.
Ideal for: Clients who want durability with sophistication and a tactile experience that feels as good as it looks.
- Thermally modified pine
Pine offers more character in its grain, often featuring visible knots and rustic charm. Thermal modification enhances its natural pattern, darkening the wood and improving its resistance to warping.
While it may not be the top choice for high-touch surfaces like benches due to resin content, it adds texture and personality when used thoughtfully.
Ideal for: Those who appreciate a bold, natural aesthetic and don’t mind a bit of wood movement over time. Pine brings a cottage warmth that’s both nostalgic and grounding.
- Thermally modified aspen
Aspen is a sauna favorite for good reason. It remains relatively cool to the touch, doesn’t splinter and has a silky-smooth finish post-modification. Thermal treatment turns its pale tone into a soft caramel, deepening its visual appeal.
It’s low in resin and odorless, making it perfect for those sensitive to strong wood scents.
Ideal for: Wellness purists and families, especially those with kids, who want the safest and most skin-friendly wood available.
- Thermally modified magnolia
Magnolia is a rare and elegant hardwood, prized for its unique grain structure and luxurious tone. When thermally treated, its veining becomes more pronounced, offering a richly textured, boutique-style finish.
Though not always used throughout the entire sauna, it’s a showstopper when used strategically, for example, behind the heater or along a feature wall.
Ideal for: Clients looking to make a design statement or incorporate elements of bespoke luxury into their space.
A Commercial Example: Kolm Kontrast, Vancouver
Our commitment to craftsmanship extends far beyond private residences. One of our most meaningful projects to date is Kolm Kontrast, a refined public wellness space in the heart of Vancouver. Built for high traffic, daily use and an elevated sensory experience, the sauna at Kolm needed materials that could deliver on all fronts. Durability, hygiene, warmth and design integrity.
We chose thermally modified Aspen for the sauna interior, a decision driven by performance as much as by aesthetics. Aspen’s smooth, splinter-resistant surface and cool-to-the-touch feel make it exceptionally comfortable for guests cycling through heat sessions. The thermal treatment enhances its longevity, tone and structural stability, ensuring that even after hundreds of uses, the sauna still looks and feels like a sanctuary.
Design-wise, the caramel hue of thermal Aspen beautifully balances Kolm’s minimalist architecture. Paired with ambient lighting, the sauna reads contemporary and warm, exactly what we envisioned.
Aspen also offers another key advantage in a commercial setting: it’s hypoallergenic and low in resin, making it ideal for all users, including those with sensitivities.
This space has become not just a local favorite, but a case study in how modern wellness can meet timeless materiality.
Want to see it for yourself? Book an experience at Kolm Kontrast →
Why Theraluxe Chooses Thermal Wood
We didn’t choose thermal wood to follow a trend. We chose it because it made our saunas better, for our clients, for their homes and for the kind of wellness rituals they want to build.
We’re one of the few sauna builders in Canada actively pushing thermal wood as a design standard and we stand behind it at every level: performance, aesthetic, longevity and sustainability.
Whether you’re building a home sanctuary or outfitting a commercial wellness retreat, thermal wood brings unmatched value.
Final Reflections: Build Your Wellness Space With Intention
A sauna isn’t just about heat. It’s about what surrounds you when the world quiets down. It’s about the materials that hold the warmth. The textures you feel when your body starts to soften. The environment you return to, again and again, to rest, recover and reconnect.
At Theraluxe, we believe materials matter. Not just for beauty, but for what they help you feel.
Thermal wood delivers more than durability, it delivers depth.
🔗 Ready to build your own refined wellness space? Explore our custom saunas and experience the difference thermal wood makes.
