I checked my IRC and couldn’t find anything detailing “roof” cantilever distances. I’m building my house and have these specs:
–1 1/2 story basic rectangular home.
–8′ 1st floor ceiling.
–10″/12″ roof pitch.
–2″x10″s for 2nd floor joists. (Spacing varies.)
–around a 4′-0″ kneewall upstairs.
–Building width = 28′-0″
–NC climate (20 psf snow load, I believe)
How far can I cantilever the 2″x10″s? I’ve seen charts dictating how far I can cantilever a “WALL & roof assembly”, but the dead load in my situation is much less, so I’m assuming the max distances should be more. If I can make it to around 4′-10″, the kneewall will align with the 1st floor’s exterior wall. If they’re no charts on this, I know I’ll have to have it stamped. Any engineers who can give an educated guess on my max cantilever distance?
Replies
I am not an engineer.
But in building it such that the kneewall is above the exterior wall, the roof loads are transferred thereby and this is not the sort of true loaded cantilever you are concerned about. So long as your joints are tight and well fastened, I have no doubt you can design it this way.
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Sorry, I was vague... The rafters were not going to be notched to rest on the kneewall. I'm assuming that the rafters must be notched (birdsmouth cut?) to lay flat on the kneewall for the kneewall to count as a bearing point.Even if I do notch the rafters, I would still need a chart or a PE to tell me how far I can cantelever the 2nd floor joists. (I'm hoping there's a licit chart!)Mark
An engineer from another forum answered.He said I could cantelever 4'-10", as long as the dead space behind the kneewall wasn't living space (aka: no dormers) and I had at least a 2:1 ratio on the 2"x10" floor joists (inside:cantelever). If I wanted to add dormers, the floor joist spacing would have to be at least 12" oc and should be double checked.Mark