Hi folks,

I bought a house in Berkeley, California, built in 1921. Our first winter spent in it was pretty terrible–we were simultaneously constantly freezing cold and paying hundreds of dollars a month for heating the house. We’d like to do at least some insulation before the winter, to hopefully make this winter a little less miserable.

The house is built on a hill, on a crawl space. The crawl space varies in height, in some places it’s tall enough to stand up, in other areas there isn’t much space between the crawlspace and the ground at all. It’s not encapsulated, though when an earthquake retrofit was done, they covered a lot of the vents with plywood and did not cut holes in them.

I’m thinking rockwool or fiberglass insulation in between the floor joists is our best bet–it will insulate the floor and also deaden the sound, which is a concern since our floors are very bouncy/noisy. There are a couple of questions I have about this:
– how much should I worry about condensation on the bottoms of the joists?
– looking at the rockwool installation manual, they recommend also installing polyiso over the joists and taping the seams. Is that a general recommendation?
– how do I avoid rats nesting in the insulation? Obviously we try to keep them out from under the house, but they’re pretty clever little buggers.
– is there anything I’m not considering?

Thank you!