I have a detached mother-in-law suite being finished. The exterior walls have three 2x6s stacked. I believe the bottom is the sill plate. The anchor bolts go through there. Then there is a second layer. Each anchor bolt has a ~3-inch gap around it in this level. Then a third layer on which the wall is built.
The gaps in the second layer with the anchor bolts go through to the exterior siding. This seems like a likely ingress for rodents, not to mention drafts.
Is there any issue with me filling these gaps with moderately expanding foam? There are also some gaps under the sill plate where it interfaces with the concrete. I assume I can fill this with steel wool or something else to keep mice out?