FEMA Building Science releases new Three-Dimensional Roof Snowdrifts Design Guide

Following a series of heavy snow and wind events in February of 2015, a FEMA team assessed four partial school building collapses in the Greater Boston area. In all four cases, the partial collapses were due to roof snowdrift loading.

When following the current ASCE 7 minimum load requirements for three-dimensional snow drifts, the FEMA team observed and documented that in two cases 3-D drifts cannot be determined.  In this new design guide, FEMA provides guidance for determining 3-D roof snowdrift loads through design examples.   The procedures identified are consistent with the intersecting drift provisions expected in the 2022 edition of ASCE 7. In the interim until the published revisions, these provisions are intended to serve as best practice guidance for design professionals.   

The Three-Dimensional Roof Snowdrifts Design Guide is available here.

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