SIP R-Values (Calculated R-Values)

The following information is from the Structural Insulated Panel Association

SIP Thickness 4 1/2” 6 1/2” 8 1/4” 10 1/4” 12 1/4”
EPS 14 21 28 35 42
XPS 20 30 38 48 58
Polyurethane * * * n/a n/a


*R-values vary between SIP manufacturers slightly

**Consult the panel manufacturer to obtain R-values


  • 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.
  • For further explanation on SIP thermal performance and whole wall R-values, please see R-values in the Real World

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