Spray foam or fiber glass batts for crawlspace?
I have a circa 1900 house on the Pacific NW coast built with old growth Douglas fir, post and beam construction, fir subfloor, (new) oak strip tong and groove flooring with penetrating wax oil finish.
The 1st level floor was very cold last winter! I have a forced air furnance in the basement floor vents on the 1st floor and attic vents on the 2nd floor.
About 70% of the house footprint is underlain by an on-grade, vented crawlspace over the ground. The crawl space has 10inch joists with 24inch centers; the walls of the crawl space are wood and go to the ground. Beams are set in concrete. The remaining 30% of the footprint has a concrete basement. There are existing fiberglass batts in the crawlspace and black plastic vapor barrier on the ground, but both are poorly installed, old, torn and smelly.
I have evidence of rats in the basement and crawl space. I plan to remove all the old insulation and vapor barrier, inspect the crawl space for damages, make the repairs and re-install new insulation.
My question: spray foam or more fiberglasss? I want no more nesting places for rats, high quality insulation, and I don’t want to re-do this again. If the foam is actually as good as advertised, it will be cost effective and provide a better air barrier and better insulation.
My concerns: off-gassing from the sprayed foam, inability to remove foam later for any un-expected repairs, locking in moisture in either the flooring or in the crawlspace, risk of problems from wood-boring insects…
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