vapa-chek approximate r-values commercial building applications Flat metal roof Vapa-Chek R-rated blanket With Ceiling Without Ceiling^ Summer R (m2K/W) Winter R (m2K/W) Summer R (m2K/W) Winter R (m2K/W) No Insulation 0.6 0.4 0.1 0.1 55mm 2.7 2.1 1.5 1.5 75mm 3.2 2.6 2.0 2.0 100mm 3.7 3.1 2.5 2.5 domestic housing applications Pitched metal roof with horizontal (flat) ceiling Vapa-Chek R-rated blanket Summer R (m2K/W) Winter R (m2K/W)    Vented     Non-vented    Vented    Non-vented No Insulation 0.7 0.5 0.3 0.4 55mm 2.9 2.6 1.8 2.1 75mm 3.4 3.1 2.3 2.6 100mm 3.9 3.6 2.8 3.1 Pitched metal roof with cathedral (raked) ceiling Vapa-Chek R-rated blanket Enclosed Rafters* Exposed Rafters" Summer R (m2K/W) Winter R (m2K/W) Summer R (m2K/W) Winter R (m2K/W) No Insulation 0.4 0.4 0.4 0.4 55mm 2.6 2.0 1.6 1.5 75mm 3.1 2.5 2.1 2.0 100mm 3.6 3.0 2.6 2.5   ^ R0.2 is attributed to the reflective foil as recommended in BRANZ Appraisal certificate No.00/016 which concludes that buildings incorporating roofing systems without ceilings experience some form of air movement due to convectional effects, ventilation and internal influences. * Enclosed rafter systems have an enclosed airspace below the Vapa-Chek of at least 100mm. " Exposed rafter systems have no airspace, but it is assumed that the insulation is allowed to recover to its full thickness (i.e. battens are equivalent to insulation thickness). Note: The above calculated system thermal resistances should be used as a guide only and are based on tables within Appendix E of AS2627.1. The calculations do not take into account thermal bridging effects at battens, purlins, etc.