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Every component of the roof (i.e.: GI sheet, concrete, insulation,
air space, sheetrock/gypsum, acoustical tiles, etc.) has a given
R-value based on its thickness. Basic HVAC data reference books will
provide the R-value or the K-value for most construction materials.
If you do not have any reference books, we will be happy to tell you
the R-value of materials you are considering.
| Example: | Resistance | |
| (m2 K)/W (h ft2 °F)/Btu | ||
| External Air Film Coefficient | 0.055 | 0.31 |
| Concrete Slab (2400 kg/m2) | 0.714 | 4.06 |
| Horizontal Airspace (1.5 in/3.81 cm) | 0.94 | 5.34 |
| Acoustical tile (false ceiling) | 0.021 | 0.12 |
| Internal Air Film Coefficient | 0.162 | 0.92 |
| Total Thermal Resistance (ΣR) | 1.892 | 10.75 |
| Overall Thermal Transmittance (1/ΣR) | 0.529 | 0.093 |
| (U-Value) | ||
