PhotonAir is an air-open reflective insulating breather membrane which combines the thermal performance of multifoil insulation with Klober Permo air underlay, for use on the cold side of the building in roofs and walls. PhotonAir is constructed with high density glasswool at its core, encapsulated between a perforated reflective lower layer and Klober Permo air. Installed in the same way as a standard roofing tile underlay, PhotonAir is water tight and upgrades the thermal insulation whilst removing the risk of condensation. PhotonAir is ideal for difficult to insulate buildings as it can be installed without a vapour barrier and can also be installed without the need to counter batten so there is no change in roof height. A unique feature of PhotonAir is that it is air-open, making it more breathable than other insulating breather membranes (air-open membranes allow more water vapour to pass than air-closed). NHBC accepts the use of membranes certified as both air and vapour-open without the requirement for supporting ridge or high level ventilation. Properties Length: 10m. Width: 1.2m. Roll size: 12m2. Thickness: 33mm. Weight: 12kg. Roll diameter: 400mm. Core rValue: 0.97 W/m.K. Fire performance: Class D - EN 11925-2. Water vapour resistance: 0.22MN.s/g. The use of high density glasswool at its core gives PhotonFoil a number of benefits over polyester based multifoils: Easier to cut and screws without snagging. Better »90/90 thermal performance. Fire resistance - A1 non-combustible core. PhotonAir Core R value 0.97 M2K/W. Core R value with 1 air space 1.76 M2K/W. Water vapour resistance 0.22 MN.s/g. Emissivity 0.05. Has achieved LABC registered details. Tested to BS EN16012:2012 A1:2015 including »90/90.