When a floor over is poorly air sealed, air can leak through a number of locations, such as the band joists, structural framing, and knee walls. Air leaks can lead to a host of issues, such as cold floors, freezing pipes, and chilled duct runs that prevent the HVAC system from working properly. A poorly sealed floor cavity has a significantly reduced R-value and isn’t much better than a floor cavity with no insulation at all. Air sealing the floor cavity properly is key.
In this application the spray foam is applied directly to the underside of the roof. Because of the foams high per inch R-value as well as being an air barrier at 1 inch and a vapor barrier at 2 inches this method is also very popular in half story retrofits because of the 2×4 cathedral ceiling rafters. Cathedral ceilings can add an element of charm and grandeur to any home,