Blown-In Insulation Tell your friends about this story .
Cellulose blown in under pressure probably fits that bill, as well as blown expandable foam.
Polyurethane or 'urethane' has been around for years as a varnish, an expandable waterproof glue and as a more highly-expandable foam insulator. It's excellent as an insulator for filling a cavity completely. It can be too good, because it's expansion capability is powerful, it can bow or blow out a piece of loosely nailed sheet rock and it can put the squeeze around window frames, to the point that you might not be able to slide the sash. You can set stones in a wall with it, although it eventually deteriorates with exposure to sunlight. You can buy polyurethane foam in aerosol cans from your local hardware store, and it now comes in low-expansion formulas to avoid the problems mentioned above.