S2S, S3S and S4S Lumber – What Gives?

Article - November 28, 2006

sleeping-on-woodAs this picture implies, lumber terminology can venture into boring territory. But it’s a necessary evil and if you want to make informed purchases, you must have at least a rudimentary understanding of how wood is graded and sold. One terminology set you’ll run into refers to how much work has been done to a board prior to purchasing and that’s exactly what emailer Skee was confused about when he wrote me:

In your show dedicated to the lumber store, the nice lady at the counter mentioned some terms you didn’t cover. Specifically, S2S, S3S and S4S. Yet another stumbling block for the newbie. Could you demystify these terms as well?

The SxS designation simply refers to how many sides have been pre-surfaced. S2S= surfaced two sides, S3S = surfaced three sides and s4s = surfaced four sides.

S2S –  The board has been run through a planer producing two flat faces, but the edges are left rough.

S3S – The board has been surfaced S2S first, then one edge is ripped straight (also known as SLR1E or straight line ripped one edge).

S4S – The board has been surfaced on both faces (S2S) and received a rip on both edges, resulting in a board with two flat and parallel faces and two flat and parallel edges. This is the stuff you usually find for sale in the hardwood section of the big box stores like Home Depot and Lowes.

So what should you buy? Well it might depend on where you shop. If Home Depot is your only option and you want red oak, S4S is the only game in town. If you want your material in a more rough state, you’ll need to check out your local hardwood dealer. Personally, I like the wood to be as rough as possible. By milling in my own shop I am certain I’ll end up with perfectly-flat boards and in many cases they’ll be thicker than 3/4″. Pre-milled stock tends to hit that 3/4″ figure on the nose. To make matters worse, since wood constantly moves those S4S boards that were once nice and flat are usually anything but by the time their in your shopping cart. And did I mention you pay a huge premium for that milling service? So if at all possible, invest in a planer and a jointer as it saves you money and headaches in the long run.

Check out this video for more basic lumber terminology and purchasing tips.


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