Standards

Design guide offers details on rain loads and ponding on roofs

April 22, 2024

The American Institute of Steel Construction and the Steel Joist Institute recently released a comprehensive roof design guide addressing rain loads and ponding.

Design Guide 40, Rain Loads and Ponding provides guidance for designing roof systems to avoid or resist water accumulation and any resulting instability. It includes an in-depth review of rain loads and ponding effects to help design professionals properly and efficiently design for ponding on roofs constructed with structural steel, open web steel joists, and joist girders.

It also contains several recommended methods of analysis that can be used to consider the effects of ponding, methods of design accounting for ponding effects, and a presentation of the SJI Roof Bay Analysis Tool, along with design examples that illustrate the concepts discussed.

Design Guide 40 is available for download at aisc.org/dg.

Sign up for Building Design+Construction Newsletters