Benefits of polyurethane spray foam insulation:

 Air Barrier

control air leakage into and out of the building envelope. Air barrier products may take several forms:

• Mechanically-attached membranes, also known as house wraps, usually a polyethylene-fiber or spun-bonded polyolefin , such as Type is a generally accepted moisture barrier and an air barrier (ASTM E2178).
• Self-adhered membranes, which are typically also a water resistant barrier and a vapor barrier
• Fluid-applied membranes, such as heavy-bodied paints or coatings including polymeric based and asphaltic based materials
• Closed-cell medium density spray-applied polyurethane foam, which typically provides insulation as well
• Some open-cell spray-applied polyurethane foam that are of high density
• Board stock, which includes 12 mm plywood or OSB, 25 mm extruded polystyrene, etc.

Among the common insulation materials only foam insulation and cellulose can provide air barriers.