Calculated R-values for generic structural insulated panel (SIP), including 7/16” oriented strand board (OSB) on each side. The R-value of each OSB facing is R-0.55.
Expanded polystyrene (EPS) is Type I per ASTM C578-11.
Extruded polystyrene (XPS) is Type IV – Type X per ASTM C578-11.
For polyurethane, polyisocyanurate, and extruded polystyrene, the tests must be done on samples that fully reflect the effect of aging on the product’s R-value. To age the sample, manufacturers must follow the procedure in paragraph 4.6.4 of GSA Specification HH–I–530A, or another reliable procedure.
R-Values may vary by manufacturer and will vary by actual SIP thickness. Please consult SIP manufacturers for individual product R-value information and SIP thicknesses available.
R-values do not include wall coverings (interior or exterior) and/or air film values.
All listed R-values are at mean temperature of 75° F.