Why so much shaking ?

crawl space shear wall

This home has substantial shaking from front to back during the earthquake several years ago.

The blueprints showed a full height foundation wall up to the floor joists in the area that had excessive shaking.

Upon inspection, I found a strip-footing with a 2 x 4 framed wall, approximately 3′ high, up to the floor joists. The framed wall was sheathed with 1/2″ plywood on both sides. My assumption is that the builder failed to pour the wall and obtained the engineers and/or building departments approval to substitute the double sheathed wall for the poured concrete wall.

Since the original construction, this home has had a problem with excess moisture in the crawlspace. A prior homeowner and/or contractor did work to increase ventilation.

It appears in order to increase cross ventilation, the sheathing has been cut out between every stud bay.  As a result, the sheathing is worthless

home inspection bellevue

Close up view of damaged sheathing and double sided shear wall

My recommendation was for a review by a structural engineer and repairs as needed