Homeowners and builders appreciate this type of insulation for its ability to permeate every nook and cranny of walls and attics. Every tight corner, sharp angle, or other obstruction can be easily negotiated during the wet application process. In a matter of minutes, the spray foam expands and conforms to the space it occupies. Correctly installed, open cell spray foam insulation significantly increases the sealed envelope of the home. A better seal means conditioned air stays in and seasonal air stays out.