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SESK: Stuff Everyone Should Know · sesk.info/wood-surfaced-s2s

In lumber grades, what does "S2S" mean?

Surfaced two sides by a planing machine.

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  1. Sawn on two sides only
  2. Surfaced on two sides ✔
  3. Stress-graded to 2

Why: S2S is lumber planed smooth on two faces. S1S is planed on one side. The other common sizing codes are S1E and S2E for edges, and S4S for all four sides.

Huh, didn't know that: Surfaced lumber is also called dressed lumber.

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References

Answer: Surfaced on two sides. S2S is lumber planed smooth on two faces. S1S is planed on one side. The other common sizing codes are S1E and S2E for edges, and S4S for all four sides.

  1. Wood Handbook: Wood as an Engineering Material, FPL-GTR-282 (USDA Forest Products Laboratory, 2021) research.fs.usda.gov/treesearch/62200
    Surfaced lumber has been surfaced by a machine on one side (S1S), two sides (S2S)
    Checked 2026-10-10.

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