This is a pretty basic concept for all of our professional customers; however, there are a lot of newcomers to woodworking and carpentry who find it confusing when they are just getting into it.
What Is S4S Lumber?
For starters, a standard “2×4” does NOT measure 2” by 4”, but is now actually 1 1/2” x 3 1/2”. The rough sawn boards actually are a full 2” thick by 4” wide, called nominal size, then they are milled – or surfaced – down to 1 1/2” x 3 1/2”. In the 1920’s, mills began planing the lumber, some on all four sides, hence the term “S4S.” (“surfaced four sides”) In use as wall studs, many of them were surfaced on only two sides, or “S2S.” This was to ensure an even wall thickness, while the width (2”) of the stud really didn’t matter if it varied. There were no standards then, but the lumber was generally surfaced to 1 5/8” x 3 5/8”, or 1 5/8” x 7 5/8”, etc.
How Lumber Sizing Became Standardized
Similarly, finish boards were also surfaced to less than their nominal sizes. A “1 x 10” would actually measure about 7/8” x 9 3/8”. This all became standardized in 1964, when framing lumber such as 2 x 4s, were all milled to 1 1/2” x 3 1/2” (or other width, such as 7 1/4”, etc.) Board thickness also became standardized at 3/4”. I’m sure many of you have done repairs or renovations on older homes, and found the subfloors to be 7/8” thick, not 3/4”. In really old homes, you may have encountered wall studs at a full 4” thick, requiring you to add strips to the modern studs to keep the wall thickness equal.
How We Sell Lumber at Barney & Carey
Today, most lumberyards do not sell rough lumber, especially for framing and pine finish. At Barney & Carey we do stock a lot of dry, rough pine in various thicknesses, for use in our own shop, or for our craftsmen woodworking customers. Pine trim boards must all be surfaced before use, and most customers will only buy it that way. We usually stock hardwoods in the rough, allowing us to mill them to whatever specs the customer requires. I wrote a blog last year on rough lumber, which you can also check out.
Understanding Board Feet and Hardwood Thickness
Rough hardwoods are sold by the “board foot.” One board foot is equivalent to a piece that measures 1” thick x 12” wide x 12” long. Thicknesses are measured in “quarters,” which are 1/4” increments. So, you may hear boards described as “4/4 x 8,” or “5/4 x 6,” or “12/4 x 10,” etc, meaning that, say a piece of Cherry that measures 5/4 x 8 x 8 is 1 1/4” thick, 8” wide, and 8 feet long. “16/4” Red Oak then is a full 4” thick. When hardwood boards have been milled to “S4S,” they are then sold as, say “1 x 8,” not “4/4 x 8.”
One More Thing Before You Apply a Finish
One last consideration on planed lumber is what is referred to as “mill glaze,” the hard shiny surface left by the planer blades. Despite how nice it may look, it is important to sand the boards with fine sandpaper to remove the glaze before applying a finish, to allow proper absorption of stain, and adhesion of paint or varnish.
I hope I have been able to make this topic understandable. Using the terms correctly will identify you as someone who knows about lumber!
Joe and Richard, two of our shop craftsmen, have been building me a farm style kitchen table, using 8/4 Quarter Sawn White Oak for the top. (It’s taking forever, because customers’ projects always take preference over anything for the owners.) I’m currently hand sanding and finishing it with polyurethane, and it will be a beauty! I’ll post photos in my next blog.
Keevin Geller, CEO
Barney & Carey Co.
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