I am having a house built. A friend said that she had "double insulation" done in her home and found that her heating bills were much lower than everyone else's on her street who had their houses built at the same time.
I spoke to my builder and was told that above my garage they are already putting R30 so they could not put anymore. I was also given a price to upgrade to R30 in the attic and cathedral ceilings.
How do the ratings on insulation work - in other words what the hell is R30, is this good enough ?