Bought a mid 1970's vintage house in the Seattle area last April. The house
has had ongoing problems with rats in the crawl space. If the assortment of
insulation between the joists is any indication, some has been replaced at
least twice, likely from this problem, and a bunch of it is torn/pulled
down/soiled now from the animals as well. It goes without saying that the
goal is to keep rodents out of the space, and I am working on that (just
found one primary point of entry that was missed by TWO exterminators that I
know of, and probably more). However I plan to have ALL the fiberglass
removed & replaced with new insulation. I am wondering if there is any type
of insulation, maybe a rigid foam board material, or something sprayed on,
which is resistant if not impervious to rodents getting into it, on top of
it, pulling it down & nesting in it. Any helpful insights into this
appreciated.

Dan