What is the minimum anchor bolt size and spacing?

What is the minimum anchor bolt size and spacing?

• A. 1/2 in. and 2.4 m OC
• B. 3/8 in. and 1.0 m OC
• C. 5/8 in. and 1.2 m OC
• D. 3/4 in. and 3.0 m OC

Answer: (A)

Anchor bolts connect the sill plate to the concrete foundation, so you want a size that provides enough withdrawal resistance and a spacing that distributes loads along the length of the wall. The smallest bolt that still offers adequate resistance for typical residential loads is 1/2 inch in diameter. Using anything smaller would weaken the connection and increase the risk of uplift or movement under wind or seismic forces. Spacing the bolts no farther apart than 2.4 meters (about 8 feet) on center ensures the load is shared among bolts and prevents the sill from lifting or shifting between fasteners. This distance keeps the connection stable along the wall and helps transfer forces into the foundation effectively. On-center spacing means measuring from the center of one bolt to the center of the next, which is the standard way to specify uniform placement along the sill. That combination—1/2 inch diameter with 2.4 m on-center spacing—meets the typical minimum requirements for securely anchoring a sill plate to a concrete foundation.

Anchor bolts connect the sill plate to the concrete foundation, so you want a size that provides enough withdrawal resistance and a spacing that distributes loads along the length of the wall. The smallest bolt that still offers adequate resistance for typical residential loads is 1/2 inch in diameter. Using anything smaller would weaken the connection and increase the risk of uplift or movement under wind or seismic forces.

Spacing the bolts no farther apart than 2.4 meters (about 8 feet) on center ensures the load is shared among bolts and prevents the sill from lifting or shifting between fasteners. This distance keeps the connection stable along the wall and helps transfer forces into the foundation effectively. On-center spacing means measuring from the center of one bolt to the center of the next, which is the standard way to specify uniform placement along the sill.

That combination—1/2 inch diameter with 2.4 m on-center spacing—meets the typical minimum requirements for securely anchoring a sill plate to a concrete foundation.