We are getting ready to re-insulate our attic and are hearing about a new spray on foam application. Basically, all the blown in insulation is removed and a spray on foam is applied to the underside of the roof and covers all vents and openings. This encapsulates the house and is reported to be much more energy efficient. However, we have always heard about the need for a house to breathe as well. Since all the vents are covered, there would be no ability for the house to breathe. We are also concerned that the foam would not allow heat to dissipate from the shingles and reduce roof life. We'd be interested in your thoughts on this.