Thermo-Spruce

Ask us which bench board to reach for and Thermo-Spruce comes up fast. Take Nordic spruce, thermally modify it with heat and steam near 400°F until the moisture and the sap are driven out, and you are left with a thicker, denser board that holds its shape, sheds water, and will not weep pitch onto the back of your legs. That last part is the whole reason it earns a spot on the bench, where plain spruce never could.

The heat treatment darkens the pale wood to a soft amber and keeps the light, even Scandinavian grain that suits a clean modern build. It pulls triple duty: tongue-and-groove STS4 cladding for walls and ceiling, 5/4 SHP for benches and floor, and 2×6 S4SEE bench, backrest, and skirting stock milled with eased edges. There is even a brushed-and-waxed black profile if you want the walls to recede and the heater to be the thing you see.

The boards marked Thermory come from our friends at Thermory. See where they’re made, and everything else they make for your sauna, on our Thermory page.

This is part of why we went big on thermally modified wood across the whole shop: it does outdoors and indoors, season after season, what untreated boards only manage for a while. If you are weighing thermo-spruce against thermo-aspen or alder for your seats, call us at (844) 565-1113 and we will tell you which one fits your room and your budget.

*Free samples available! Select ‘sample’ and ‘free shipping for samples’ under any wood profile.
*Most wood orders qualify for free shipping with any heater purchase.