What does a Class 1 Fire Resistance Rating mean?
Class 1 Fire Resistance Rating is given to materials that conform to test standards set by the American Society for Testing and Materials (ASTM E-84) for acceptable flame spread and smoke development for combustible construction materials. ASTM E-84 is a similar test to UL-723, NFPA 2255, or UBC 8-1. Testing is accomplished by suspending a sample of material in the tunnel of a horizontal test chamber. The material is exposed to gas flame on one end of the tunnel for 10 minutes. The flame progression on the material is compared to selected standards and calculations designed to produce a flame spread rating. Smoke from the fire in the tunnel is measured in the exhaust stack via a light beam to establish smoke developed ratings. There are three classes of acceptability for rigid foam used in construction: Class 3 is unacceptable, Class 2 is the minimum standard required for residential construction, and Class 1 is the best classification available. Murus SIP foam cores have a Class 1 Fir
