If your looking for a way to assure your home insulation is tight enough to block all air coming in or leaving the home, then Expanding Foam Insulation is the way to go. This type of insulation is great because you can spray it in and it will expand to cover even the tiny holes most normal insulation won’t get. When spraying it in it goes in wet and expands and adheres to both the walls and wood beams in the attic but also will adhere to itself so other sprayed in insulation becomes zipped shut essentially. This option may be a bit more expensive than the static squares or blown in variety but in the long run you save more money.