Softwood Lumber Classification

Softwood lumber comes from "evergreen" trees (such as Pine and Spruce) with needle-shaped leaves that stay green year round. Hardwoods come from deciduous trees (such as Oak and Maple) and have broad leaves that turn brown and fall from the tree in the winter months.

All grading systems for softwood are based on the appearance, strength and rigidity of the lumber. There are several grading systems that have been promoted by different professional associations in various parts of the country; but all of them must conform to the US Dept. of Commerce American Lumber Standards.

Softwood is generally graded into very detailed classifications, but the homeowner and do-it-yourselfer will find the broadest classifications to be the most useful.

Type of Lumber   Description
Rough   Sawn, trimmed and edged. Faces are unsurfaced and show saw marks.
Surfaced   Rough lumber that has been surfaced by a planing machine.
Worked   Planed lumber that has been patterned, matched or shiplapped.
Shop and Factory   Millwork lumber intended for applications such as trim molding, door jambs and window frames.
Yard   Known as "structural lumber", this classification is intended for structural framing, concrete forms and sheathing. It is further subdivided into these sub-categories:

Boards - Must be < 1 inch thick and 4 to 12 inches wide

Planks - Must be > 1 inch thick and > 6 inches wide

Boards - Width and thickness must both be > 5 inches