Insulating Exterior Wall Cavity on existing house
We just bought a colonial in RI that was built in 1970. The inspector said there was a bout 3" of fiberglass in the attic but mentioned nothing about the walls. I checked a few outlets and did not see any signs of insulation or a vapor barrier.
I plan of sealing off air leaks in the attic with spray foam and then blowing in cellulose up to the recommended R49 or slightly higher since I'll be already there.
As for the walls, what are my options? I've heard blow in cellulose is very common. I realize this would probably be best left to a pro but would this method make sense if there's no vapor barrier? Could the cellulose potential cause a mold/rot issue?
Are there any other options, such as void filling foam?