Model and local building codes used in the United States provide guidance and requirements for the safe use of materials and systems used in buildings. Since the 1970s, foam plastic thermal insulation, including polyurethane and polyisocyanurate, has become an important element in the building envelope and is specifically regulated by the current building codes. This document gives an overview of building code fire performance provisions that control how foam plastic insulation is used and how it must be protected in use. While information is provided on tests mandated by the building codes to measure the fire performance of foam plastic insulation used in buildings, keep in mind that there are other considerations addressed by building codes such as physical properties of products.