Masonry Magazine August 2010 Page. 34
Installing
Seismic Anchors by the Code
BY PAUL CURTIS
MILLIONS OF PEOPLE LIVE IN HIGH SEISMIC ZONES IN THE UNITED STATES. THERE ARE SIX SEISMIC ZONES, LABELED A THROUGH F. ZONES A AND B REQUIRE NO ADDITIONAL SEISMIC ANCHORING REQUIREMENTS. Zone C requires the engineer to isolate the sides and top of anchored veneer from the structure, so seismic forces resisted by the structure are not imparted to the veneer. For Seismic Zones D, E, and F the International Building Code requires a single, continuous nine-gage (.156-inch or 5/32-inch) reinforcing wire in the horizontal mortar joint of brick veneer walls. This wire needs to be tied to the backup with an anchor and spaced with one anchor a maximum of every two square feet with a maximum vertical spacing of no more than 18 inches. Typically, you will find these anchors spaced every 16 inches on center. The Code also requires that the veneer anchors must be within 12 inches of wall edges near openings. The Brick Industry Association (BIA) recommends eight inches. Most seismic anchors have clips that are welded or clipped to wire anchors, and bent notches in flat anchors like the two shown below.