What are the requirements for anchorage of wood sill plates and wood wall sole plates in the IRC?


Anchorage of wood sill plates and wood wall sole plates are called out in Section R403.1.6 of the IRC, requiring ½-inch anchor bolts embedded 7 inches into concrete or grouted cells of masonry and spaced at no more than 6 feet on center. A minimum of two anchor bolts are required in each plate and an anchor bolt is required within 12 inches but not closer than 7 bolt diameters from each plate end. Although nuts and washers are required to be installed, there are no minimum requirements. However, for braced wall lines in Seismic Design Categories D0, D1 and D2 and for townhouses in Category C, larger 3” x 3” plate washers are required for use with the anchor bolts (see Section R602.11.1) installed in accordance with R403.1.6.1. The use of the larger plate washers is one simple and cost-effective method to design braced wall panels with increased load capacity for uplift and lateral loads from wind and/or seismic events which may be incorporated into the design of braced wall panels in other geographic regions as well. Remember that anchorage is only as good as the weakest link in the continuous load path to the foundation, which may include continuous sheathing, hurricane clips, hold downs, strapping for floor-to-floor connections, and other components.