Dow Froth Pak Sealants (green stripe box) are excellent at sealing air leaks, preventing moisture infiltration and keeping dust and pests out. Sealants typically need to be covered with an additional fire barrier to meet code requirements.
Dow Froth Pak Insulation (red stripe box) is also excellent at sealing and provides insulation at R-6 per inch thickness. In addition, Froth Pak Insulation is formulated to provide extra fire protection with a Class A fire rating; this allows it to be sprayed up to 2 inches thick in basements, crawl spaces and attics without the requirement of a separate fire barrier. For specific requirements contact your local building code office.
Dow Froth Paks produce a sprayable closed cell foam that seals gaps and prevents air and moisture infiltration. Once you seal and lay down a base of spray foam insulation you can add bulk with fiberglass batt to build R value (known as flash & batt). With no air leakage you get the full R value from your materials.