Can SIPs be used in fire-rated assemblies?
Although SIPs are made of combustible materials – oriented strand board (OSB) and expanded polystyrene (EPS) insulation – many manufacturers have tested their SIPs in fire-rated wall and roof assemblies.
For example, Premier SIP’s code report from NTA notes that our SIPs “may be used as a component of a fire-rated assembly if suitable evidence and details are submitted and approved by the authority having jurisdiction.” Contact us for information on tested wall and roof assemblies that meet the one-hour fire-resistance requirements of ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials.
Meeting the one-hour fire test typically requires attaching two layers of gypsum (depending on the thickness of the gypsum) to the SIP. The gypsum protects the EPS foam core from melting in the heat of a fire, for the duration of the fire rating period.