One of the largest growing uses of spray polyurethane foam (SPF) insulation is in residential attics and crawl spaces. As with all other foam insulation applications, this use is regulated by building codes to assure that occupants are properly protected from the risk of fire. In order to demonstrate compliance with these requirements, the spray foam supplier typically performs fire tests, the results of which are submitted to an evaluation organization, such as the International Code Councils Evaluation Services (ICC ES), for review. A product’s performance is assessed against an Acceptance Criteria meant to clarify code requirements or to provide a technical basis for products or systems that are alternates to what is specified in the code. Through a public hearing process, the ICC-ES developed the Acceptance Criteria for Spray-applied Foam Insulation (AC 377).