Snow Drift Windward Fetch
Snow Drift Windward Fetch
(OP)
For calculating snow drift on the windward side of a lower roof, ASCE 7-05 tells you to use the length of the lower roof in Fig 7-9 (ASCE 7-05 7.7.1). If you have a situation where there is a long higher roof, followed by a relatively short lower roof, followed by another high roof, would you use only the length of the lower roof, or would you use both the first higher roof plus the lower roof on the windward side of the second low/high step?






RE: Snow Drift Windward Fetch
RE: Snow Drift Windward Fetch
You may, depending on you exact configuration, also have a leeward drift at the first step from high to low.
RE: Snow Drift Windward Fetch
Mike McCann
McCann Engineering
RE: Snow Drift Windward Fetch
RE: Snow Drift Windward Fetch
For determination of drift surcharge, I will use the more conservative approach of using the lower roof area and everything adjacent to it at an equal or higher elevation. If anyone knows of any Code or Code Committee that has taken a position on this question, I would be interested in that.