Low slope roof ponding in high snow areas

[Thedg]

I'm having trouble finding design examples for low slope (1/4 / 12) roof member design in areas with high snow loading. The codes I've seen say to use "approriate snow" loads when considering winter ponding. Does this mean full roof snow? Does it include drifting? Also, how much liquid water is to be considered? The buildings I typically work on use steel joist framing members w/ metal decking, roof drains for primary drainage, and scuppers for overflow. If anyone has any info to share, I'd be very grateful.
Thanks

 

[haynewp]

ASD has guideline to use for checking ponding that are fairly straightforward. There is also SJI's "Structural design of Steel Roofs to Resist Ponding Loads".
I don't know why you would use anything less than the full roof snow at typical areas and I would check ponding at drift locations for dl + basic snow + drift.
All drainage systems are usually assumed blocked for water ponding. There is usually a rain on snow surcharge to be included in the basic roof snow load. Ways to calculate joist inertias can be found in Vulcraft's joist manual, which I believe require a reduction by ASD when checking ponding. Don't forget to do a separate deck strength check also. And that's all I have to say about that.