The Fenestration and Glazing Industry Alliance (FGIA) has updated a technical information report determining design wind loads on exterior fenestration and cladding systems. The report, AAMA TIR-A15-23, Overview of Design Wind Load Determination for Fenestration Systems, provides details for exterior fenestration and cladding systems and covers Boundary Layer Wind Tunnel (BLWT) testing and its use. This document was last updated in 2014.

The FGIA report update coincides with window failures at several San Francisco high rises due to intense windstorms in March.

“Over the years, improvements in predicting wind velocities and patterns have been made so that many buildings can be reliably designed using the data and formulas provided in the 2016 and 2022 editions of ASCE/SEI 7,” says Rich Rinka, FGIA’s technical manager of Fenestration Standards and U.S. Industry Affairs and staff liaison for the document’s developing group, the FGIA Design Wind Loads on Fenestration Task Group. “BLWT testing is still necessary under certain conditions that cannot reliably be predicted.”

Wind load is a principal load to which components and cladding, exterior fenestration and cladding systems are subjected. Knowing how wind acts on the building envelope is vital to ensure a structurally adequate design is achieved.

The update coincides with window failures at several San Francisco high rises due to intense windstorms in March. Winds up to 70 mph whipped through the region, cracking glass and sometimes breaking windows completely. An independent engineering firm is investigating the failures at seven buildings.

The failures could have been caused by a number of things, from design flaws to flying debris, says Megan Stringer, president of the Structural Engineers Association of Northern California.

“We don’t know if all of the failures are happening because of the same reason or if all of them are happening for very different reasons,” she says. “Once we figure out what they are, we have to see if they can be detected by any kind of realistic inspections, and then we can better understand the extent of the problems and what the next steps should be.”