Anchor bolts connecting a sill plate to the foundation serve to:

The sill plate connection is where a wood-framed building is joined to its foundation, and anchor bolts are what make that joint capable of resisting anything other than gravity. Wind produces uplift on the roof and lateral pressure on the walls; seismic events produce cyclic lateral loading at the base. Without anchorage the building simply rests on the foundation and can slide off it or lift at the edges, which is one of the classic failure modes in both wind and earthquake damage surveys. Gravity load, by contrast, is carried by direct bearing of the plate on the foundation and needs no fastener at all. Keeping those two roles distinct — bearing carries weight down, bolts hold the structure on — is the concept this question is testing.

Anchor bolts resist uplift and lateral displacement, the forces produced by wind and seismic events. Gravity loads travel through direct bearing of the plate on the foundation, so the bolts exist for the loads that would otherwise move the building off its base.

Sill plate anchorage transfers lateral and uplift forces between the wood framing and the foundation. Bolts are specified at a maximum spacing and within a set distance of plate ends and splices, and are used with washers and nuts drawn tight.

Bearing Holds It Up, Bolts Hold It Down. Gravity needs no fastener; wind and earthquakes do.

Check for washers as well as bolts. A nut bearing directly on the plate can pull through the wood under uplift, which is a commonly tested and commonly found deficiency.

• •Assigning gravity load to the anchor bolts
• •Confusing anchorage with grounding or moisture separation
• •Confirming bolts are present without checking for washers and tight nuts