I got a 12" concrete drill bit and 5 cans of DAP Max Fill spray foam. I drilled into the floor and except for one hole, it was nothing remarkable. But there was considerable space in the lower NW corner of Compartment SE at the floor. And then there's a huge cavity under the under porch hatch door in Compartment SW.
The ladder one and possibly others are going to require a supply of polyurethane foam that greatly exceeds the cans that I bought today.
I filled seep holes in Compartment NE. One of them looked like a rodent tried to burrow there because it was wide.
