Proctor Air is a vapour and air permeable underlay (VPU) for pitched roof applications. While the majority of VPUs in use today utilise an airtight, vapour permeable, film layer to achieve their performance, Proctor Airs’ SMS (Spunbond Meltblown Spunbond) structure allows high levels of airflow in addition to the transport of moisture vapour, making the formation of condensation virtually impossible.
Independent studies of the effect of air permeability have confirmed that lofts using air permeable underlays have more consistent air-flow through the roof than those found in traditionally ventilated lofts, according to BS5250, so whatever side of the vents/no vents debate you sit on, Proctor Air has it covered. Its heavyweight 170gsm three-layer structure also containing a hydrophobic in every layer, gives a Class W1 rating under the latest EN13859-1 specifications.
Key Features:
Vapour Permeable: Proctor Air has an Sd-value of 0.02m and a vapour resistance of 0.1 MNs/g, making Proctor Air one of the highest performing vapour-permeable membranes on the market.
Fully Air Permeable: Air permeable membranes allow air movement through the roof, as well as allowing moisture to escape by diffusion. This means that condensation is far less likely to form on the membrane itself, and also allows the membrane to deal with much higher moisture levels within the building, for example during the drying out period.
Highly Water Resistant: Proctor Air is rated W1 under EN13859-1, and has a hydrophobic additive in all 3 layers. The membrane can be left exposed to provide temporary weather protection to the building envelope for up to four months (see FAQs, page14-15). Proctor Air has a Hydrostatic Head of water of over 1m as recommended by NFRC Technical Bulletin 6. It is good practice not to leave the underlay exposed longer than necessary
Wind Uplift Resistance Complies With BS5534: Based on fully independent 3rd party testing, Proctor Air can be utilised across the UK. This, in addition to no requirement for high level ventilation or the use of a vapour control layer, ensures Proctor Air remains the simplest and most cost effective method of achieving regulation compliance.
More Uniform Airflow Than Vents: The air permeability of Proctor Air means a non-ventilated roof fitted with Proctor Air allows a more consistent air flow through the roof than a roof ventilated as per BS5250, without expensive and time consuming ventilation hardware fitted to the roof.
No VCL Required: Installing Proctor Air will mean that a vapour control layer is not required for non-ventilated cold pitched roof constructions.
15 Year Warranty: Proctor Air’s 15-year warranty provides peace of mind on any project
