Spray polyurethan foam does effectly prevent all six of these heat transfer methods from occurring. These should be the mechanisms by which you judge insulation, in addition to their R-Value. If you're uncertain about installing spray foam insulation, Energy Star has a map that recommends levels of insulation by R-value and cost-effectiveness in the United States.
Typical roof coating dry film thickness vary from paint film thickness (plus or minus 3 dry mils) to more than 40 dry mils. This means a roof coating actually becomes the top layer of a composite roof membrane and underlying system. As such, the roof coating is the topmost layer of protection for the membrane, receiving the impact of sunlight (both infrared and ultraviolet (UV), rain, hail and physical damage.
Ames® Roof Coatings are premium elastomeric coatings that seal out moisture, renew old surfaces and even save energy. We have products specifically formulated for all types of roofs including; Wood, Tar, Metal, Rolled Roofing, EPDM Rubber, Foam and many other surfaces. Ames’ coatings form a waterproof seal to preserve and protect your roof. Our white roof coatings reflect sunlight, substantially reducing roof temperatures. Ames® products are environmentally friendly, waterbase, non-toxic, VOC-free and water cleanup.
Spray foam insulation systems effectively seal walls, roofs, corners and other surfaces, creating a more comfortable household because it provides a barrier against drafts and associated pollen and dust. Long-term, properly installed spray foam won’t change its form or shape, meaning it will deliver the same benefits that it did years—or even decades—after being installed, while other insulation materials may settle and create future gaps in the insulation. 
Note: The practice of foam insulating the attic has raised eyebrows in the building industry because "standard" roofing techniques call for the attic to be ventilated; however, in a vented attic situation it will become approximately 130 degrees in the summer. There's no reason for an air-conditioning and vent-ductwork to have to work in that type of severe conditions. By applying Icynene right on the underside of the roof deck, the severe temperatures no longer exist in the attic. In short, the attic is now a "conditioned" space of the house that is just as comfortable as any other room in the home. This is called a "Compact Roof", which means you can frame right up against it. The one drawback of using expanded foam on the inside of the roof is that this will cause the temperature of the shingles to rise, but how much is not yet known. And how much damage a rise in temperatures could cause is debatable.

Roof Spray Foam Insulation

×