Why are those long planks of wood called “2 by 4s”?
What units are we measuring here? 2 what by 4 what? Regardless of what units were using the proportions seem all off. 2 by 4 seems to imply that its a rectangle where the longer side is twice the side of the shorter side, but that doesn’t describe this wood size at all. The long side is quite a big longer than twice the side of the shorter size. So I’m confused. Then there are other sizes of wood, like 2 by 6s, and I see similar issues there too.
Someone please explain what’s going on here.
It’s dimensional lumber so it’s not actual size but before they started shorting them for profit, they were called 2x4s because they measured 2 inches x 4 inches. 4x4s, 6x6, 1x8, 2x12, etc. They all represented actual dimension of the lumber but you’ll notice that today, they are basically 1/2 inch short in every dimension so a 2x4s actual measurement is 1 1/2" x 3 1/2".
If you tear apart the walls or look in the attic of a home built in the first half of the 20th century, you’ll see lumber that actually measures their stated size.
It used to be you’d buy a 2x4 and then face it by taking 1/4" off all sides so it would be pretty. Now the lumber yards do that. Don’t get me wrong the lumber industry is fucked and new lumber is inferior to old lumber, but be mad about timber forest management instead of the yard facing your lumber for you.
Obligatory XKCD: https://xkcd.com/3138/
Please let such a thing never exist!
Had a 100+ year old house built for a steel mining company. Full cinder block siding on 2 stories and a basement. Joists in the basement were full size 2x10s nestled snugly between steel reinforced concrete joists (I forget the length on center). Had to replace some sub floor on the second floor under the toilet. More steel reinforced concrete joists. The nukes ever start flying I’m hightailing it back there and busting in… provided they didn’t reinforce the door.
Inspector came to look at the house for some reason and was impressed to see a house built in the 50’s with a giant length of walnut(?) something like 8”x 12” by 20’
I have an old house on my property that has a similar piece of wood holding everything up.
They don’t/can’t build like that anymore.
The “2x4” name comes from the size of the rough cut timber when it is sawed out of the tree trunk. It starts as two inches by four inches. However, by the time the board makes it to the lumber yard, it has been milled down to 1.5 inches by 3.5 inches in order to remove bark, gashes, and other imperfections. Same thing with “2x6” boards or larger.
Now, this rule really only applies to building timbers. Other means of measurement apply if you were to go looking for, say, hardwood boards.
This is what I was taught as well. It’s a very intentional “not quite 2x4”, but saying that every time gets tiring haha
2 inch tall by 4 inch wide. That includes what you lose with the saw used to cut it and what it loses in processing. So its not exactly 2 inches by 4 inches. Don’t feel stupid asking, especially if you measured a plank and didn’t understand why it wasn’t literally 2X4 lol.
