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Comment by engineer_22 | Hacker News Reader

I was going to agree with you, as a university trained engineer it seemed absurd to count drywall towards structural calculations, but then I did some research.

TIL gypsum board is given some shear strength credit in the code books:

https://up.codes/s/shear-walls-sheathed-with-other-materials

I wouldn't have guessed it, I wouldn't trust it if it was close to failure, but there it is.

I think the least attractive aspect is how drywall fails catastrophically, and once it's broken the strength can't be restored. This is probably why I didn't expect it to be counted in structural calcs.

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Weak elements secured in multiple places become strong ones. Potentially extremely strong ones.

The workbenches in my shop consist of multiple cheap, crappy pressed-wood folding tables from Office Depot, secured to each other on multiple sides with equally-cheap metal brackets. You'd think this would result in a rickety, unsafe platform that would blow apart in a stiff wind or buckle under light vertical load, but instead they are stouter in all three dimensions than most actual retail-grade workbenches. (And I don't have to feel bad about drilling into them!)

I can see drywall working exactly the same way, given enough studs and enough nails. The problem to be solved -- and the lesson I learned when I hacked these workbenches into existence -- isn't necessarily insufficient rigidity, it's too many degrees of freedom.

Yeah, I wouldn't really count it for much on actual load bearing walls, but it is noticeable on non-load bearing walls, they become more stable with drywall.

The most noticeable place I've seen it is in garages; the ones that are drywalled on the inside don't seem to lean as much as those that aren't.

well that's good to know! i had an implicit assumption of load-bearing walls in my prior comments, which is why they skew the way they do. of course for non-load-bearing walls, drywall is perfectly fine, but i'd still choose plaster & lath (backed by plywood for seismic reasons) over drywall.

for a dream home, i'd love steel or mass timber for the exterior framing to reduce (maybe eliminate) interior load-bearing needs, so that interior layout is maximally configurable while still allowing lots of windows. expensive, but dreamy!

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