Thermo-Spruce 1×4 Tongue and Groove Sauna Wood | STS4 Nickel Gap | 2 to 10 ft

PROSAUNAS Thermo-Spruce tongue and groove 1×4 STS4 profile creates a bold look and is recommended for sauna walls and ceilings. Thermo-Spruce wood has a smooth refined finish and a traditional rustic charm with its characteristic rich amber color and highly figured knotty look.

Why builders choose it

• Ideal for saunas
• Greater durability
• Resists warping
• Free from chemicals
• Eco-friendly
• Ideal moisture content
• Narrow and angular grooves
• Natural wood

At a glance

Your options, explained

Pick the board length in the drop-down above. Every length is priced per board. Order a 1 ft sample piece first ($2.77) to see the color and profile in your own light.

About the wood and profile

Thermo-Spruce is spruce that has been heat treated (thermally modified) with no chemicals. It turns a deep brown and becomes more stable and moisture resistant, a budget-friendly way to get the dark thermo-wood look.

STS4 is the Finnish tongue and groove profile with a narrow, angular nickel-gap groove that gives clean, modern lines.

How much do I need?

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Each board covers 3.1″ of wall face, so you need about 387 linear feet per 100 sq. ft. Add about 10% for cuts and waste.

• Measure each wall: width x height. Add the ceiling: width x depth.
• Subtract large windows and glass doors.
• Multiply the total square feet by 3.87 to get linear feet, then add 10%.
• Divide by your board length to get a board count.

Example: a 6 ft x 8 ft sauna with 7 ft walls has about 244 sq. ft. of walls and ceiling. That is about 1,039 linear feet with waste, or 130 boards at 8 ft (about $2,880.80 at list price). Call us and we will check your list before you order.

Build the rest of your sauna

• Thermo-Spruce sauna wood: paneling, benches and trim in the same species
• Tongue and groove sauna paneling
• Sauna bench wood
• Sauna trim and moulding

How shipping works

All the sauna wood in your order ships together by freight, and you pay one freight charge for the whole order, not per board: 15% of your sauna wood total, with a $149 minimum and a $795 maximum. Freight is free once your sauna wood reaches $6,000. It is worked out for you at checkout.

1 ft sample pieces ship by parcel, so you can see the color and profile before you order a full room. Freight is delivered curbside; long boards are unloaded by hand, so plan for a helper. Alaska and Hawaii ship at a higher freight rate. Call us for lead time.