Which option correctly states the minimum anchor bolt size and spacing?

• A. 1/2 in. diameter with 2.4 m OC
• B. 3/8 in. diameter with 1.8 m OC
• C. 5/8 in. diameter with 1.2 m OC
• D. 3/4 in. diameter with 3.0 m OC

Answer: (A)

Securing a sill plate to a concrete foundation requires a balance: the fasteners must be large enough to resist pull-out and uplift, but you don’t want to go bigger than necessary. The smallest size that still provides adequate strength is a half-inch diameter bolt, which gives enough resistance for typical residential loads. The spacing of 2.4 meters on center is set to distribute that resistance evenly along the wall, preventing long gaps where the sill could lift or shift. So, using half-inch bolts with 2.4 meters on center meets the minimum strength needs while using the simplest, most economical hardware that still satisfies the required performance. A smaller bolt would be undersized; a larger bolt or tighter spacing would exceed the minimum standard, and a much wider spacing would risk insufficient hold.