Hello, Sauna Season.
When designing a custom backyard sauna, choosing the right interior timber is one of the most critical decisions in the build. For decades, clear western red cedar has been the gold standard—celebrated for its rich aroma, natural decay resistance, and timeless aesthetic.
However, as modern sauna architecture evolves and the cost of clear grade cedar fluctuates, Imbue™ thermally modified wood has emerged as a high-performance alternative for interior cladding, benching, and trim profiles.
Both timbers offer exceptional, time-tested characteristics in high-heat environments. Understanding how their technical specifications compare will help you select the ideal wood for your backyard retreat.
Choosing the Right Timber for Sauna Walls & Benches
The ideal timber for a sauna hot room needs low thermal conductivity, excellent dimensional stability through rapid temperature shifts, and a clean, resin-free surface.
Clear Western Red Cedar (The Traditional Standard)
Thermal modification is a chemical-free process where timber is baked at high temperature (215°C) in a vacuum-sealed, steam-heated kiln.
This process permanently modifies the wood's cellular structure:
Hemicellulose breaks down: Removing the nutrients that support rot and mold growth.
Equilibrium moisture content drops: Reducing total water absorption (holding a maximum saturation around 12%).
Stress points are released: Significantly reducing internal tension, shrinking, and swelling.
The result is a lightweight, dark-toned timber with enhanced dimensional consistency across board profiles.
Technical Comparison: Imbue vs. Clear Western Red Cedar
While both clear Western Red Cedar and Imbue perform exceptionally well in saunas, their physical movement profiles and market availability differ.
Feature / Metric | Clear WRC – Mixed Grain (MG) | Clear WRC – Vertical Grain (VG) | Imbue™ Thermally Modified Radiata Pine |
|---|---|---|---|
Width | 5.0% | 2.4% | 3.0% |
Thickness | 2.4% | 5.0% | 2.0% |
Resin & Pitch Content | Pitch-free. Contains no sap or pitch pockets. | Pitch-free. Vaporized during heat processing. | |
Surface Temperature | Low thermal conductivity; classic comfort on bare skin. | Low thermal conductivity; feels slightly cooler to the touch. | |
Moisture Absorption | Porous; absorbs atmospheric moisture over time. | Reduced hygroscopicity; caps at 12% saturation during prolonged moisture exposure. | |
Surface Finish & Texture | Low splintering; fine-sanded surfaces may raise grain slightly over time. | Fine Sanded finish. Smooth surface engineered for comfort. | |
Environmental | Sustainable when responsibly harvested; completely natural with zero industrial processing required. | Chemical-free heat modification; sourced from FSC-certified forests with exceptional long-term carbon sequestration. | |
Best Climate | Moderate environments; suitable for all regions but requires diligent maintenance in high-humidity zones. | Harsh, wet, or marine environments; engineered to handle severe freeze-thaw cycles and intense moisture. | |
Rot Resistance | Exceptional Natural Resistance. Organic thujaplicins and extracts protect against decay, providing a 20–25 year service life with proper upkeep. | Maximum Biological Resistance. Thermal alteration neutralizes nutritional hemicellulose, preventing fungal colonization and delivering 25–30+ years of performance. | |
Pricing & Value | ~60% higher than Imbue | ~80%-90%+ higher than Imbue | Predictable & Cost-Effective. Premium performance at a lower price point. |
Key Performance Considerations
1. Dimensional Stability & Profile Fit
All natural wood expands and contracts when exposed to moisture and steam (löyly). However, Imbue’s 3% tangential and 2% radial movement profile keeps tongue-and-groove cladding tight and benching flat over years of thermal cycling. While clear cedar rivals this stability in vertical grain profiles, Imbue offers consistent dimensional performance across every board.
2. Touch Comfort & Fine-Sanded Profiles
3. Moisture Behavior
4. Cost & Availability
One of the most significant advantages of Imbue today is cost predictability. Clear western red cedar prices fluctuate widely based on timber harvesting constraints, with clear grades currently sitting 60% to 90%+ higher in price than Imbue. Imbue offers a luxury, high-durability finish without the extreme price volatility of top-tier cedar.
Recommended Profiles for Sauna Builds
Whether designing a minimalist modern sauna or a traditional Scandinavian retreat, Imbue is available in versatile profile options.
Walls + Ceilings
Tongue & Groove Cladding: Ideal for seamless vertical or horizontal wall and ceiling installations.
TG27 180x17.5
TG27 136.5x17.5
TG27 90x17.5
Benches
Moulder Blanks
Fine-sanded stock can be used for bench frames, seating surfaces, backrests, and trim detailing.
Imbue™ Key Features:
1. Heat tempered for durability, stability, and long-term performance.
2. Durability Class 1 (EN350) and Class 2 (AS5604) – above ground.
3. 96.5% dimensional stability.
4. High grade quality timber with mainly clear faces and minimal knots.
5. 15-Year Warranty*.
*Imbue Cladding and Screening Maintenance Guide
*Imbue Radiata Global Warranty
6. FSC® certified timber from responsibly managed plantations.
7. Light weight and easy to install.
8. Easy to maintain and lower maintenance costs over its lifespan.
9. Naturally chocolate brown, will silver with age unless finishes are applied.
10. Accepts most finishes including water and oil borne stains and paints.
Frequently Asked Questions
Is thermally modified wood safe to use in a high-heat sauna?
Yes. The thermal modification process relies entirely on heat and steam—no chemical additives or synthetic preservatives are used, ensuring zero toxic off-gassing when exposed to sauna temperatures.
Do you need to coat or seal Imbue timber inside a sauna?
No. Sauna interior cladding and benches are best left completely raw. Imbue’s lower equilibrium moisture content provides natural durability while allowing the wood to breathe and maintain a comfortable tactile surface.
What care and maintenance is required for Imbue sauna wood?
Choosing the Ideal Timber for Your Sauna
If you prefer deep, consistent dark tones, excellent dimensional stability, and significant cost savings without sacrificing performance, Imbue is an outstanding, modern choice.
Bring on the steam.
Thermally modified flatsawn wood for siding, soffit, panelling & decking
Imbue™ is flatsawn Radiata pine, thermally modified to enhance its natural durability and stability, creating sustainable materials built to last.
This heat-treated wood cladding is available in both Imbue™ and Imbue™ Light, each with a curated collection of program colours selected by Fisher’s coating specialists.
