Wood for Saunas: Clear Cedar vs. Imbue Thermally Modified Wood

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)

Clear western red cedar (WRC) has earned its legendary status for good reason. Unlike soft pines or firs, western red cedar contains no pitch pockets or sap resin, meaning it will not weep sticky residue when heated above 80°C. It is naturally lightweight, decay-resistant, and offers an iconic aroma that many sauna traditionalists consider essential.

Imbue™ Thermally Modified Wood (The Engineered Alternative)

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
Tangential Movement (Width)	5.0% (Flat Grain)	2.4% (Radial Thickness)	3.0% (Width)
Radial Movement (Thickness)	2.4% (Radial Thickness)	5.0% (Tangential Thickness)	2.0% (Thickness)
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.
Pricing & Value	~60% higher than Imbue	~80%-100% 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

Both timbers perform exceptionally well under high heat. Imbue offers a subtle density reduction that makes it feel slightly cooler to the touch than standard cedar. To ensure maximum seating comfort, Imbue bench profiles come fine-sanded from the factory, providing a smooth, silky surface designed for long-term comfort.

3. Moisture Behavior

It is a common myth that thermally modified wood is completely impervious to water. Like all natural timber, Imbue absorbs moisture during prolonged exposure, but its cellular modification caps total water saturation at 12%. This reduced absorption ensures wall boards and benching maintain their structural alignment over time.

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

170.5mm cover

TG27 136.5x17.5

127mm cover

TG27 90x17.5

80.5mm Cover

Benches

Moulder Blanks
Fine-sanded stock can be used for bench frames, seating surfaces, backrests, and trim detailing.

150x25mm Cover

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 Against Rot*

*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?

Maintenance is straightforward. Wipe down benches with a damp cloth after use and leave the sauna door or vent open to dry the room. For periodic cleaning, use warm water and a mild, sauna-safe soap. Any light surface scuffs or water marks can be easily refreshed with a quick touch-up using fine-grit sandpaper.

Imbue Resources

Choosing the Ideal Timber for Your Sauna

Both clear western red cedar and Imbue thermally modified wood are top-tier choices that deliver fantastic results in custom backyard saunas. If you prioritize traditional cedar scent and classic light-amber aesthetics, clear cedar remains an iconic material.

If you prefer deep, consistent dark tones, excellent dimensional stability, and significant cost savings without sacrificing performance, Imbue is an outstanding, modern choice.

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.

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