So what size will a 2x4 be after that? 0.75x1.25 just doesn’t roll off the tongue, does it?
In seriousness, nominal vs actual sizing is just terrible. Do places outside of North America do this too?
In seriousness, nominal vs actual sizing is just terrible. Do places outside of North America do this too?
https://www.inchcalculator.com/actual-size-of-dimensional-lu...
That's just an old wives tale.
Lumber shrinks for money reasons, older lumber is bigger [1] with sequential revisions to the standard decreasing it's real size [2] [3] (the difference between 2in and 15/8in in strength is minimal however you can keep doing that math, and they did, to go down from 2in to 1.5in over a century).
[1]: https://www.reddit.com/r/mildlyinteresting/comments/vv9atu/t...
[2]: https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDeta...
https://www.youtube.com/watch?v=WaJFudED5FQ
They claim that the change was driven by railroad shipping charges, and wasn't based on drying, but on pre-planing the rough lumber to reduce shipping cost. They further claim that in 1919 the US Dept. of Agriculture studied the issue and ended up defining a national standard for what the post-planed dimensions of a 2x4 should be. And they further claim that it took until the early 1960s to settle on a new standard that matches what we use today.
The pre-planing is a common claim, but I don't believe it. They can make lumber whatever size they want - of course they need to plane it, but they just make it larger to account for that. Still the planing excuse it one they like to use because it doesn't show "them" as trying to cheat us.
I understand the origins of this. But I've never understood why we haven't moved on to actual sizing given the scale at which standardized lumber dimensions are produced