We are getting the outside foundation excavated and would like to know. First: what are the proper process that need to be followed for insulating the wall from outside? Second: for the foundation wall what R value we need? Third: if outside insulation is done do we need to insulated the inside wall in the basement also?
Answer:
Exterior wall insulation should have a metal flashings above it to keep run-off from getting behind it and it should go down to within a foot or so of the drainage tile where a sloped portion of insulation should be installed to shed water away from the house. I would use 1.25" rigid foam and then certainly insulate on the inside so you can introduce a vapour barrier.
