Snow drifting in International Residential Code

[Daniel-PRE]

Is there any reference to snow drifting in the IRC? I'm looking in 2018 and I haven't found a single reference. Is it not considered on these structures? How has the design been limited to avoid snow drifting? I don't know of any sections that require the roof structure to all be at the same elevation. Any insight would be greatly appreciated! I tried looking through the forum to find if this had been discussed, but all I found was combining snow and live load for deck designs...

 

[phamENG]

I'm not aware of anything that requires it to be considered directly under the IRC. It should be, and any engineer submitting a design in snow country that doesn't consider it is probably being negligent....but for a contractor's special with all prescriptive, table based member sizes and connections I hope/think it must be baked into those tables?

 

[Daniel-PRE]

That's what I'm wondering, the scope of an IRC building is pretty open-ended when it comes to shape and stories and little roofs. Can't tell if they assume the homeowner will go take care of a drift or not, haha.

 

[ChorasDen]

IRC limits prescriptive application to areas with a ground snow load less than or equal to 70psf (2018 R301.2.3). In addition, there is a limit for structural wall height of 10ft (2018 Table R602.3(5)). Trussed roof length is limited to 40ft (several sections in Chapter 8).

It's a really large leap to make, but if we follow those prescriptions listed above to calculate drift, the largest drift surcharge I can calc out is 67psf.