The minimum thermal resistance (R-value) of materials installed in the wall cavity between framing members and continuously on the walls shall be as specified in Table C402.1.3, based on framing type and construction materials used in the wall assembly. The R-value of integral insulation installed in concrete masonry units shall not be used in determining compliance with Table C402.1.3.
“Mass walls” shall include walls:
- Weighing not less than 35 psf (170 kg/m2) of wall surface area.
- Weighing not less than 25 psf (120 kg/m2) of wall surface area where the material weight is not more than 120 pcf (1900 kg/m3).
- Having a heat capacity exceeding 7 Btu/ft2 • °F (144 kJ/m2 • K).
- Having a heat capacity exceeding 5 Btu/ft2 • °F (103 kJ/m2 • K), where the material weight is not more than 120 pcf (1900 kg/m3).