Are the crawl space perimeter walls reinforced with plywood or OSB panels?
Perimeters walls must be reinforced to prevent the house from falling over during an earthquake. This is typically done by installing plywood or OSB sheathing panels on the outside of the walls. Older homes often did not use this type of sheathing. Instead sidinboards were used, but not attached to prevent failures. The building codes recommend the installation of ½-inch plywood or OSB panels to the inside face of the walls in strategic locations to strengthen the perimeter walls.
