Edit: The Rockwool didn't substitute fiberglass -- inner walls are normally not insulated, they're just made of 2x4s with sheetrock on top. I could probably hav

Edit: The Rockwool didn't substitute fiberglass -- inner walls are normally not insulated, they're just made of 2x4s with sheetrock on top. I could probably have saved some money by just using regular fiberglass in all inner walls.