Nominal versus actual measurements
Once upon a time, when you bought a 2 x 4 piece of lumber it was 2”-thick by 4”-wide. Over the years, the amount of wood in each board got pared back from those “nominal” sizes to their current “actual” measurements. If you stick a tape measure on a 2 x 4 you’ll discover that it’s actually about 1 1/2” by 3 1/2”. You’ll need to take this missing material into account when drawing up plans and calculating the amount of lumber to buy.
Did you want CCA, ACQ, or CA PT?!?
Pressure-treated (PT) lumber is the name of the greenish wood popular for outdoor woodworking projects. The other acronyms refer to the chemical formulation used as a preservative. CCA stands for chromated copper arsenate, an old formula no longer used for consumer lumber. It’s been replaced with ACQ (alkaline copper quaternary) and (CA) copper azole. (See also, Screws for Pressure-Treated Wood.)
Can you really rip wood?
No, it’s not a test of superhuman strength. To “rip” a board means to cut it lengthwise along the grain. You’ll do this if a standard size piece of lumber, for example, is too thick for the task at hand.
You may also come across a related term: kerf. This refers to the thickness of wood that’s removed – i.e. turned to sawdust – by the blade of a saw.
Who are Mr. Phillips and Mr. Robertson anyway?
It’s fine to ask Junior to grab you a star-, flat-, or square-head screwdriver, but you really should know their real names if he asks. For the record, the star-pattern is called a Phillips; the square is a Robertson. See also, “Types of Screwdrivers.”
Butt joint versus mitre joint
There are a number of different ways to join two pieces of wood. The type you choose depends on esthetics, strength, and expediency. The simplest joint is the appropriately named “butt joint”: one piece of wood butts up against the other and the two are nailed or screwed together. In a mitre joint, the ends of two pieces of wood are cut on matching angles (“mitred”), usually at 45 degrees, then joined flush, like a picture frame.
Bow, cup, checks, and knots
Wood is a natural material and, as such, can have a lot of imperfections. Each, of course, has its own name:
•Bow – a curve from one end of a board to the other along its face (i.e. laid flat on the ground, the board will have a high point in the middle)
•Cup – a curve along the grain (i.e. viewed from the end, the board has a half-moon or cup shape)
•Checks – gaps along the grain where one layer (growth ring) has separated from the next
•Knots – remnants of branches from when your board was a tree, higher grade (and higher priced) lumber will have less knots
Stud, header, sill, joist, beam
While most lumber starts out as a 2 x 4 (or 2 x 6), depending on where it’s used it’ll earn a new title:
•Stud – the parallel vertical lumber that makes up a wall frame
•Header – horizontal pieces (usually two nailed together) laid on their edge to provide support over a window or door
•Sill – the boards at the base of a window or door opening
•Joist – parallel lumber that constitutes the bulk of the framing for a floor or ceiling
•Beam – the main, load-bearing horizontal supports for everything from decks to houses
