Snow Load Questions

[Perception]

Hello everyone,

I have two general questions about snow load calculations in ASCE 7-10.

1. In section 7.6.1 it is mentioned that:

"Roofs with an eave to ridge distance, W, of 20 ft or less, having simply supported prismatic members spanning from ridge to eave shall be designed to resist an unbalanced uniform snow load on the leeward side, and the windward side shall be unloaded."

Would a flat roof be considered to fall into this category? The terminology eave and ridge is typically in regard to a sloped roof.

2. Does the density of snow increase in the unbalanced and drift snow load cases? Similar to fine aggregates, when the wind blows one side of a pile would compact while the other side will be more loose. If this is the case then two densities need to be used for snow load calculations.

Thanks

 

[msquared48]

#1. NO, but the parapet load condition would have to be applied for any parapets.

#2. Density would not change except at the eaves, or anywhere else, where icing might occur.

Mike McCann, PE, SE (WA)