1. R Values are expressed as ⁰F^.ft²h/Btu.
2. U Factors expressed as Btu/h^.ft²⁰F. Includes air films and roofing.
3. Dead Loads include weight of metal, polystyrene and perlite concrete roof insulation. Dead loads of structural concrete are not included.

NOTES:

• Insulation values are for summer conditions, heat flow down. To calculate winter conditions, heat flow up, substract 0.39 from the R-value, then add 1.5 for air films and roof, and divide into 1 for the U-value.
• U factors are based on series-parallel heat flow caluculations defined in the ASHRAE Handbook of Fundamentals and on test data by recognized, independent test laboratories. Thermal conductivities of roof deck components are based on 40⁰F mean temperature except perlite concrete which is based on 75⁰F.
• Perlite concrete properties are bsed on constant thickness insulation. For sloped insulattion, calculate average thickness.
• The U factors shown are calculations based on thermal conductivity data derived from laboratory testing of dry materials in accordance with ASTM Specification C 177. The values shown are intended only as guidelines. Actual insulation performance for all materials and systems is affected by design of building, environment, and installation, and will be lower than calculated values.