Thermo Aspen takes the already exceptional properties of White Aspen and elevates them through a controlled thermal modification process that transforms the wood at a molecular level. The result is a timber of superior stability, dramatically reduced moisture absorption, and enhanced resistance to the biological degradation that shortens the lifespan of untreated woods. Its deep, golden-brown tone — developed naturally through the heat treatment process, with no stains or chemicals — gives it a richness that standard Aspen cannot match.

In sauna applications, Thermo Aspen maintains all the comfort advantages of its natural counterpart — cool-to-the-touch surfaces, hypoallergenic properties, and pitch-free clean air — while delivering the dimensional stability and longevity demanded by commercial installations and high-use residential saunas. For clients who expect both exceptional performance and elevated aesthetics, Thermo Aspen represents the pinnacle of the Aspen family.

Species Overview

Janka Hardness: 450 lbf | Grain: Straight, Fine
Avg Dried Weight: 28 lbs/ft³ | Odor: Virtually None
Color: Golden Brown | Resin Content: Non-Resinous

Thermo Aspen begins with the same sustainably harvested White Aspen stock prized for its comfort and purity in sauna applications, then subjects it to a carefully controlled thermal modification process that fundamentally transforms its cellular structure. The result is a timber with dramatically reduced hygroscopicity, superior resistance to biological degradation, and a rich, uniform golden-brown tone achieved entirely through heat — no stains, no chemicals, no compromises.

The thermal modification process drives out residual moisture and permanently alters the wood’s cell walls, producing a timber that absorbs and releases moisture far more slowly than untreated Aspen. This translates directly to greater dimensional stability in the demanding thermal cycles of sauna use — less expansion, less contraction, and a longer service life with fewer maintenance concerns.

All of the comfort properties that make standard Aspen exceptional are retained and enhanced. Surface temperatures remain cool to the touch. The air stays clean and odor-free. The hypoallergenic character is fully preserved. Thermo Aspen simply adds durability and visual depth to a species that was already the benchmark for sauna comfort.

Available Materials

STS A – 1X4 | T&G Nickel Gap – Wall Profile
Thermo Aspen’s rich golden-brown tone — achieved entirely through thermal modification, with no stains or chemicals — gives the 1×4 nickel gap panel a warmth and depth that standard Aspen cannot match. The shadow-line reveal adds architectural rhythm to a surface that already commands attention on its own.

• Nominal size: 1×4 | Actual size: 0.59″ x 3.54″ x 94.49″
• Face width: 3½» with ½» gap reveal | Profile: T&G / nickel gap
• Typical use: Walls and ceilings | Installation: Blind nail or clip

STS A – 1X4 DUAL | T&G Nickel Gap – Wall Profile
The dual-face Thermo Aspen panel brings the species’ deep, uniform golden tone to both faces of the installation — perfect for feature walls, glass-backed sauna designs, and open wellness environments where every surface is on display.

• Nominal size: 1×4 | Actual size: 0.59″ x 3.54″ x 94.49″
• Face width: 3½» with ½» gap reveal | Profile: T&G / nickel gap
• Typical use: Walls, ceilings, partition walls | Installation: Blind nail or clip

S4S A – 2X4 (*) | Bench Profile
Thermo Aspen retains the cool-to-the-touch comfort of standard Aspen while adding the dimensional stability that high-use commercial benching demands. The 2×4 S4S bench board delivers a smooth, splinter-free surface that performs reliably session after session without warping or checking.

• Nominal size: 2×4 | Actual size: 1.10″ x 3.54″ x 94.49″
• Profile: S4S / smooth four sides
• Typical use: Benches and platforms | Installation: Face nail or screw

S4S A – 2X6 (*) | Bench Profile
The 2×6 Thermo Aspen bench board is the premium specification for luxury sauna projects where bench comfort and visual richness must coexist. Wide boards with deep golden coloring and a flawless S4S finish create a seating surface that sets the standard for high-end sauna interiors.

• Nominal size: 2×6 | Actual size: 1.10″ x 4.72″ x 94.49″
• Profile: S4S / smooth four sides

Typical use: Benches and platforms | Installation: Face nail or screw