Snow Drifting at Low Roof

[SEARUN]

I am looking at the snow drift at a low roof. If the upper roof has a parapet do I calculate hc as the difference between the elevation of the high roof and the top of the balanced snow or is hc the difference between the top of parapet and top of the balanced snow? I would think that hc for the leeward case the high elevation should be the high roof whereas for the windward case the high elevation should be taken as the parapet. Am I correct in my thinking? See the attached pdf for a sketch and Figure 7-8 in ASCE 7-05.

 

[woodman88]

ASCE 7-05 Section 7.1 "... hc = ......(2) top of parapet...."

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.