Braced Wall Lines

Wall Bracing
Provisions for wall bracing have been a part of code since the mid-1900’s and recently these provisions have gotten a face lift. Compared to the homes of a half century ago, the average house of today is larger, more complex and it has more door and window openings (which have grown larger as well).
In 2008, Virginia adopted the 2006 Virginia Residential Code, part of the 2006 Virginia Uniform Statewide Building Code (USBC), which replaced the wall bracing provisions of the 2006 International Residential Code (IRC) with those from the 2009 IRC. Since that time the 2009 IRC wall bracing provisions have been revised. Soon the 2009 Virginia USBC will go into effect superseding the 2006 Virginia USBC. Unfortunately for those experienced with wall bracing under the 2006 Virginia Residential Code there appears to be a substantial difference in the method of calculating the amount of bracing required.
For those unfamiliar with wall bracing, it is simply strengthening the structure of the home, through the use of Braced Wall Panels (BWP), to withstand the stresses caused by earthquakes and high wind events.
Wall bracing needs to be accounted for during the design phase as it is a system that uses the entire structure of the home. Every exterior wall (as well as some interior walls) will be part of wall bracing. The floor and roof systems, used as diaphragms, are the connection between stories and each story must be braced. The connection to the foundation is crucial as well. Every exterior wall must be part of a braced wall line (BWL) and must have a calculated percentage of braced wall panels. There are several types of braced wall panels, probably the most common being wood structural panels (WSP) with portal frames being the most difficult to properly construct. There are maximum wall heights, minimum BWP lengths, maximum BWP spacing and maximum BWL spacing to be accounted for, not to mention nailing patterns. Wall bracing of today is not something you can just “wing it.”
Here at Timber Truss Housing Systems, all of our wall panels exceed nailing pattern requirements and a wall bracing layout can be provided (for all walls complying with the current code) for your house plan with your wall panel order. In some cases it may also be necessary for some window or door openings to be slightly resized or relocated to comply with code.
*The 2009 edition of the Virginia Uniform Statewide Building Code goes into effect on March 1, 2011. From what I have read, permits can still be applied for under the 2006 Virginia Residential Code until March 1, 2012.

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