I recently bought a house, and had an energy assessment done which determined that my exterior walls have old UFFI insulation that is rotting away, leaving substantial gaps and allowing heat transfer to/from outside. There does not appear to be any way to access the insulation by going up from the basement or going down from the attic to remove and replace it. Obviously, I could take down the drywall inside to get at the insulation, but I'd rather not do that if I don't have to. Are there ways of removing and replacing insulation in walls that are minimally invasive?
In a word, no. That's one of the reasons it is no longer used. Once it begins to shrink away from the edges, there is no recourse to fix the problem short of removing the drywall and taking it out, then replacing it with like fiberglass batts.