UNBOLTED SILL PLATES Sill plates are the first line of defense in holding back the lateral wall pressures from wind, quakes, and shifting soils. Without proper bolting, the rim joist will do the twist, while foundation walls do the limbo. All sill plates must be properly bolted to the top of the foundation, whether it's a block or concrete wall, spread or trench footing, or a concrete slab. Steel anchor bolts should be a minimum of 1/2 inch in diameter, embedded not less than 7 inches into the concrete, and spaced not more than 6 feet apart. An anchor bolt should be located within 12 inches of the end of each sill plate and each
