Talk:3138: Dimensional Lumber Tape Measure

I was under the impression this was actually a thing that exists, somewhere. (Separate and apart from so-called "shrink rules" used by patternmakers who create patterns for metal castings). No? JohnHawkinson (talk) 00:36, 6 September 2025 (UTC)

https://www.inchcalculator.com/actual-size-of-dimensional-lumber/ for reference --- MEL

Wikipedia has a similar table. Interestingly, if the values on this table are correct, the xkcd measure fails for the 8 x 8 board. 2605:59C8:160:DB08:988B:772A:4E5:B209 02:18, 6 September 2025 (UTC)

"I was under the impression this was actually a thing that exists, somewhere" - if doesn't exist now, it soon will. 70.115.234.146 03:59, 6 September 2025 (UTC)

Thinking that there might be a typo in the comic - It says : A "1x8" IS "3/4 BY 7 1/8", yet it should be "3/4 BY 7 1/4".

I no longer want to be a lumberjack! 2A02:2455:1960:4000:748F:2291:F005:1989 06:57, 6 September 2025 (UTC)

This reminds me of when I changed my friend’s text replacements to be slightly misspelled whenever she tried to type a common word in college. She was getting a degree in linguistics and it was SO FUNNY 《プロキシ》(XKCD中毒者) 13:29, 6 September 2025 (UTC)

She should have claimed that she was undertaking "applied linguistics" and investigating how to create a deliberate language change! 92.17.62.87 20:23, 6 September 2025 (UTC)

I was told (and maybe this is wrong), that the dimensions are intended to represent the final thickness of a wall when drywall (usually 0.5" thick) is attached to the studs. Shamino (talk) 20:58, 6 September 2025 (UTC)

I think that's just a convenient side effect. Of course, if the drywall is 1/2 thick, a wall with 2x4 studs will be 4.5 inch thick. RegularSizedGuy (talk) 22:22, 6 September 2025 (UTC)

That would be pretty ahistorical, so I think it is indeed wrong. Drywall is a relatively modern invention, and I think the standardization of 2x4s as 1.5″ thick predates it (need to check that…but even if it didn't, then it would be worse). Wood lath and plaster walls are more like 5/8″ from the stud face, if not more. And, of course, in modern American multifamily residential construction 5/8″ walls are more common, or even double-5/8″ walls (making 1 1/4″) in fire-rated assemblies. So it does not even end up being "convenient," not that a 4" wall assembly is particulary more "convenient" than a 4.5″ or a 4.125″ or a 4.75″ wall assembly…very little turns on the thickness of the stud plus wallboard, but a lot turns on the thickness of the stud cavity (insulation, space for utilities, &c.) or the thickness of the drywall (spacing of electrical outlets, mudrings, etc.). JohnHawkinson (talk) 04:20, 7 September 2025 (UTC)