S4S Lumber Sizes
Nominal Versus Finished Sizes
Note: S4S means surfaced four sides. Surfacing is most typically done by using a planer resulting in a wavy surface with several knife marks (see diagram on left) and the “S” does not stand for sanded. Here at NCWP, we do sand all 4 sides of our S4S product as well as the finished faces of all of our other millwork products.