The Basic Wind Speed used to design buildings and claddings in Southern California is highly variable, depending on which jurisdiction the project is in. Some jurisdictions define the Basic Wind Speed based on past experience; others rely solely on ASCE 7; and still others have no well-defined policy regarding this issue. There is particular variation in the areas in and around the Special Wind Regions in Southern California. Required wind speeds can vary by as much as 35 miles per hour, depending on the policy chosen by the jurisdiction; this can result in as much as an 87 percent increase in wind loads just from crossing from one jurisdiction to the next.
The shaded areas in this figure show a new Special Wind Region near Irvine and significant changes to the shape of the existing Special Wind Region along the San Gabriel and San Bernardino Mountain Ranges, as introduced in ASCE 7-22. More than a million people live in these special wind regions, several million more live in the surrounding areas, and these changes will be part of the 2025 California Building Code, so this is a critical issue that needs to be addressed.
The Structural Engineers Association of California (SEAOC) has been commissioning studies to help define the Basic Wind Speed in these Special Wind Regions. We are inviting building officials, plan checkers, and design engineers to collaborate in a charrette to discuss these changes and discuss what the appropriate Basic Wind Speed(s) should be in these areas.
The first hour will present recently completed studies that show what we have learned to date. The second hour will be a facilitated discussion to hear ideas regarding how to achieve a consistent approach to defining wind speed requirements in these areas. We are seeking ideas related to both technical recommendations and ways to organize the numerous jurisdictions in developing a common approach. We invite you to join us, share your experiences and expertise, and provide input at the charrette. The charrette will be informative, and SEAOC is offering it free of charge.
We look forward to seeing you!