Dark Thermo-Alder 5/4×4 SHP Boards — Benches, Backrests & Skirts
Finished board size ≈ 3.5″ × 1″. Each board shows 3.5″ of face. Boards come in bundles of 4 in these stock lengths (LF): 5.9, 6.8, 7.8, 8.8, 9.8. Price is per linear foot — free samples available.
Bench Planner
The calculator adjusts the actual gap to fill the depth with full boards (no ripping), while staying between 0.10″ and 0.75″. Most benches feel best with gaps around 3/8″–5/8″.
Extra covers waste, trimming, and imperfect pieces.
Includes seat boards + one fascia board along the front. Gaps are auto-optimized for full boards and efficient use of material.
Backrest & Skirt Planner
The calculator adjusts the actual gap to fill the height with full boards (no ripping), while staying between 0.10″ and 0.75″.
Extra covers waste, trimming, and imperfect pieces.
Boards run along the length. Gaps are auto-optimized so you can use full boards across the height without ripping.
Surfaces (Benches, Backrests & Skirts)
| Surface | Dimensions | Board length | Bundles (raw) | |
|---|---|---|---|---|
| Add benches, backrests, or skirts to list them here. | ||||
Bundles to Order — By Stock Length (rounded per length)
| Stock length (LF — bundle of 4) | Bundles to order | Raw bundles |
|---|---|---|
| Add benches, backrests, or skirts to see the breakdown. | ||
Grand total: 0 bundles · 0.0 raw bundles before rounding.
Order Line Items (Title / Description / Quantity)
| Title | Description | Quantity (bundles) |
|---|---|---|
| Add benches, backrests, or skirts to see line items. | ||
Specifications
Application: Interior, Sauna Materials
Use: Interior Only
Type: Standard Stock, Bench Board, Backrest, skirt, floor
Species: Alder (Modified)
Color: Light Brown
Authorized Dealer: Sauna Marketplace
Finish: Unoiled, Unwaxed
Installation type: Hidden
Profile: No Groove
Installation methods: Screw
Modification Strength: Intense
5/4x4 Dark Thermo-Alder SHP
Thickness: 1.1"
Width: 3.5
Coverage: 3.5
Testing
- Safety & Compliance
- Conforms with EC Regulation No 305/2011
- Meets EN 14915:2013 standards for solid wood paneling
- E1 formaldehyde emission class (low emissions)
- Fire reaction class D-s2, d0 (moderate fire resistance)
- Natural Material Benefits
- 100% natural solid wood (Common alder/Alnus glutinosa)
- No surface coating - authentic, chemical-free finish
- Interior use specification - perfect for sauna walls
- Technical Advantages
- Thermal conductivity of 0.12 W/(m·K) - excellent insulation properties
- Density range of 490-530 kg/m³ - solid but not overly heavy
- Sound absorption coefficient of 0.1/0.3 - helps create a quieter space
- Estonian Craftsmanship
- Manufactured by Thermory AS in Estonia
- European quality standards and manufacturing processes
- Durability
- Biological durability Class 5 according to EN 350:2016
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Building Benches Using Standard 2x4s
This sauna wood is fairly thin and requires dimensional 2x4's to build the frame underneath. That makes it cheaper, more sturdy, and you can construct it in a way that you won't see the wood.
We also like this method becuase there's no tablesaw involved.
If you are concerned about light wood showing through, you can use Western Red Cedar 2x4's or paint the 2x4s black using Supi sauna wax or SaunaLife Sauna Wax.
Include cross bracing every 16" on center. For extra long spans, consider using 2x6 material for the frame or bracing it from underneath with metal running the full length.
The recommended gap is at least 1/4" to allow airflow and drainage. It's important to note that wider gaps, up to 3/4" is best for airflow and heat distribution. This is where you'll have to weigh aestetics vs performance.
Thermory's Process
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