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Tall stud wall framing / IRC rant

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I had a meeting today in which a residential foreman argued that an 18' tall stud wall needed only be 2x6 studs on 16" centers according to the table in the IRC. Well, I'd had this discussion with the designer a week previous, where I showed him the output of an analysis that indicated a 2x8 was necessary for this framing. The designer also thought that 2x6 was okay, but didn't reference the IRC.

I looked it up tonight, just to see if the IRC was sharpening their pencils a little much again, and found that the table, R602.3.1 to be exact, does indeed show 2x6s for an 18' stud wall. Curious, I read the notes at the bottom and found the caveats listed to be almost ridiculously restrictive, such that the designs are practically unusable in a good bit of the country. Snow load must be less than 25psf - I assume this is ground snow load, since there is no formula in the IRC to convert to a roof snow load (locally we're 30). Fb must be > 1310psi. Well, even with a repetitive and size factor added, No.1 SPF - the most common stud material around me (and on the east cost, I suspect) comes out to 1308psi. Add in an E of 1.6x10^6, and the list of lumber species and grades gets mighty short - #2 S. Pine and Doug.Fir are the only framing species that fit the criteria. Here in the east there are no DF studs, and S.Pine smaller than 2x8 is found only in treated lumber and trusses without a special order. Tributary width for vertical loads must be less than 6'. Unless you've got lots of interior bearing, or are only checking gable end walls, that makes for pretty small rooms and no trussed roofs. And if it weren't obvious from the material properties, Stud grade studs are not permitted (nor are utility, construction, or No 3).

It just makes me shake my head. Even if this particular job didn't have a 17' horizontal span without a sole-to-top plate stud, and if they hadn't framed a two story wall by stacking two 9' tall walls, and if they hadn't used 2x4s, and even if it wasn't backing up brick veneer, there are still 5 different criteria that disallow the use of this chart. And yet, the chart says 2x6 on 16" centers works, so they figure it's correct, and I'm full of *expletive* for telling them they should have used at least 2x8s. Worst, with their openings they'll need 3/4T of steel to fix the problem without packing the wall to thicker than 3.5". It think the #2 S. Pine and Doug.Fir needs to be in the title, and they may as well just say "non-bearing-walls only", with a little note at the bottom for an exception for walls with tributary widths less than 6' and snow loads of 25psf or less. I know that moaning and complaining here won't get the code changed (and I'm honestly not sure whose ear to chew on to try and get it changed), but are the rest of you doing small jobs like this running into similar problems? If so, how do we fix the code language so that mistakes are less likely? Even the best inspectors can't remember all the notes and subnotes across all of the disciplines in a couple thousand pages of code.


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