DIY Projects

How is Lumber Classified?

Submitted by: Woody Wall on November 04, 2011

Board Classification

S2S - Surfaced 2 Sides - These boards have been surface planed on top and bottom.
S2S1E - Surfaced 2 Sides One Edge
S3S - Surfaced 3 Sides - These boards have been one edge surface planed on top/bottom and straight line ripped on one edge.
S4S - Smooth 4 Sides - These boards have been planed and sanded on all 4 sides to their finished dimensions and are usually sold by the linear foot.
FAS - Firsts and Seconds. Generally clear of large knots, FAS boards may be Rough cut, S2S, or S3S.
Rough - Not surfaced on any side.

Board Dimensioning

Boards are listed in most cases by their nominal dimensions. Actual sizes for S4S finished lumber should be as follows:

lumber size chart