Can a "2x4" be referred to as a "board"?

Solution 1:

Yes, in the US the word board can be used for virtually any piece of timber/lumber, regardless of dimension. I don't know what you would consider "official" when it comes to common usage, but here are some examples from various industry experts:

From Kreg Tools, which makes woodworking "tools for clamping, joining, routing, cutting, measuring, and more":

When you’re buying lumber at a home center, whether it’s in the “outdoor,” “construction,” or “board” aisle, you need to understand that the stated size and the actual size of the boards are generally not the same. That’s because all construction lumber, along with essentially every type of “board” sold in a home center, has a stated or “nominal” thickness and width, and a slightly smaller “actual” thickness and width. For example, a 2x4 board actually measures 11/2" thick x 31/2" wide, as shown in the table below.

The table is headed "COMMON BOARD SIZES" and includes nominal size 2X4.

From BobVila.com's "8 things you can make with 2X4s" (I'm sure Bob didn't write this article himself, but still):

The first thing you need to know about 2x4s: They don’t actually measure two by four! These boards, which you can find in any lumberyard or home improvement store, in lengths from 6 to 12 feet, measure two inches thick and four inches wide in their raw state, but once milled, they come out at 1½ by 3½ inches.

This "Difference Between Lumber and Timber" article takes for granted that "board" is a universally understood, generic term for all kinds of wood used in building:

Timber is the word used to refer to wooden boards in the U.K. and Australia while lumber is the wooden board for the American and Canadian denomination.

From Lee Wallender's "What Is "Dimensional Lumber" and Is It a Redundant Term?" on thespruce.com:

When we say that a board is "nominally" 2 inches by 4 inches, in essence, we are saying we have given a board a certain name, but this name does not reflect the board's physical sense.

I have not found a dictionary definition to support this, but in most cases it appears that board is used as a countable form of lumber—that is, board can be substituted for piece of lumber and boards for pieces of lumber. You can see that usage reflected in the "Lumber Buying Guide" by Lowe's, a big-box hardware store:

Treated lumber is produced for exterior use only and pressure treated for ground or above ground contact. It is resistant to rotting and insect damage. Boards can be painted or stained.

And finally, here is a screenshot from the video linked from that buying guide, "Why is a 2x4 Not 2 by 4? | DIY Basics":

Solution 2:

This is an interesting question, one I hadn't thought of before. I, an American, have some passing experience with woodworking; but not extensive, and I would have called a 2x4 a "board."

To answer your question explicitly, yes, some people call a 2x4 a "board," but "2x4 stud," as you suggest, is more common, as you can see in this Google Ngram of 2x4 board, 2x4 stud searched in the American English corpus.

However, there's probably more to this story, so I decided to look up usage on Home Depot's online catalog. Home Depot is headquartered in Atlanta, Georgia, and has locations across the U.S., Canada, and Mexico.

A search for "2x4" on Home Depot's website returns only things they call "studs," nothing called "boards." This suggests your intuition is correct.

However, searching for "board" gets you a much wider range of lumber products, including 1x10s, 1x12s, 1x3s, and 2x2s and 2x8s (but not 2x4s). So, for whatever reason, a 2x4 doesn't count as a "board" in Home Depot.

That said, you suggest the width must be "considerable" to the thickness, which isn't supported by Home Depot's classifications: Their "board" catalog includes 2x2s (a 1:1 ratio), as well as 1x2s (the same ratio as a 2x4).

So, to conclude, Americans do sometimes call a 2x4 piece of wood a "board," although they might be more properly referred to as "studs" in technical language.

(I will do more research after work today but wanted to put up my preliminary findings.)