Softwood Lumber - Grading

Rough lumber, surfaced lumber (dressed), worked lumber, shop and factory lumber and yard lumber

Rough Lumber

Sawn, trimmed and edged lumber. The faces are rough with saw marks.

Surfaced Lumber

Rough lumber smoothed by surfacing machines. Subcategories based on the number of sides and edges that have been smoothed.

s4s wood lumber

  • S1S - Surfaced on 1 Sides
  • S2S - Surfaced on 2 Sides
  • S3S - Surfaced on 3 Sides
  • S4S - Surfaced on 4 Sides


  • S1E - Surfaced 1 Edge
  • S2E - Surfaced 2 Edges


  • S1S1E - Surfaced 1 Side and 1 Edge
  • S1S2E - Surfaced 1 Side and 2 Edges


Note that S4S lumber planed and surfaced all four sides will be noticeably less than its nominal dimension.

Worked Lumber

Surfaced lumber that has been matched and  patterned.

Shop and Factory Lumber

Millwork lumber - used for molding, door jambs and windows frames.

Structural Lumber or Yard Lumber

Yard lumber used for house framing, sheathing, concrete forms.

Yard lumber or structural softwood lumber is subdivided in

  • Boards -  no more than 1 inch thick and 4-12 inches wide
  • Planks - more than 1 inch thick and more than 6 inches wide
  • Timbers - width and thickness greater than 5 inches

Related Topics

  • Miscellaneous - Engineering related topics like Beaufort Wind Scale, CE-marking, drawing standards and more

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