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Passive Purple Airtight White Edition – Airtight Membrane

Passive Purple Airtight White – Airtight Membrane. The world’s most airtight liquid vapour control membrane. BBA Certified and Passivhaus Certified Airtight Vapour Control Membrane.



  • Passivhaus certified
  • BBA certified
  • M1 class, voc free (volatile organic compound)
  • Radon barrier
  • Fire class c
  • Up to 300m2 a day per operative
  • 0.03ach (air changes per hour)
  • Adheres to any substrate

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  • Key Details

    Why Choose Passive Purple Airtight White?

    • BBA Certified And Passivhaus Certified – Airtight White is a fully BBA certified Liquid Airtight Vapour Control Membrane.
    • Radon Barrier – Airtight White offers you a perfect Radon Barrier to eliminate those nasty radon gases entering your building
    • Up To 300m2 Coverage A Day – A single installer can apply up to 300m2 of Airtight White a day using an airless spray device. This speeds up the construction time and dramatically cuts labour costs
    • M1 Class, VOC Free – Airtight White is an M1 class, VOC-free water-based product. Zero nasty chemicals make it friendly for the user and the environment
    • Fire Class C – Airtight White is rated Fire Class C, unlike paper membranes which are rated Fire Class E
    • 0.6ACH Or Under – Airtight White can guarantee you a score of 0.6ach (air changes per hour) and under! Whether you’re trying to achieve Passivhaus certification or just build to a Passivhaus standard, Airtight White is your answer
  • Description

    Now we know what you’re thinking. Is it a nasty chemical? Well, No! Passive Purple Airtight White – airtight membrane is a VOC-free, water-based vapour control membrane. It’s completely free of any nasty chemicals or fumes… What’s more, as a water-based product, cleaning your paintbrushes and airless spray device is a smooth, no mess task.

    Passive Purple Airtight White adheres to any form of construction, allowing you to achieve maximum results for your desired goal. Once dry, Airtight White forms an extremely tough yet flexible polymer, water control membrane allowing it to move with the building settlement while also being super effective against impact damage. Airtight White, airtight membrane eliminates the inevitable rips, tears, unstuck tapes, staple holes, and many repairs you would expect to find on the classic paper membranes.

    We have eradicated the need for paper, tapes and staples through this product, which eliminates all the problems that came with it (labour time, large quantity of damage repairs and waste material).

    Passive Purple Airtight White saves you money and delivers well above your goals.


  • Uses
    • Envelope Areas 

    Airtight White is an airtight coating that is spray applied with an airless spray device. It is designed to cover all areas of an external envelope (warm side of the insulation) of a building, including difficult connections in floors, walls, roofs and joist areas. As long as Airtight White is used on the warm side of the insulation, it can be applied to either face of the external envelope.

    The surface material where you apply Airtight White needs to be dust-free, solid and closed before starting the application. A closed surface implies that holes and joints need to be closed beforehand. Large holes and joints (> 5mm) can be closed with fast setting cement-based products or polyurethane foam. Small holes and joints (2-5mm) can be closed with Airtight White Liquid Brush. This is a much thicker (paintbrush applied version of Airtight White).

    After these preparations, Airtight White radon barrier membrane can be sprayed with an airless paint spray device. This fast application method allows a single operative to apply up to 300 m2 per day.

    For small projects, such as private houses, Airtight White Brush can be used with a flat paintbrush. In this case, an airless spray device is not needed.

    The wall/ceiling connections also need to be made airtight, especially when the connections are made of two different types of construction materials such as red brick/concrete or steel/concrete. Different construction materials react differently to changes in humidity and temperature, moving at different rates, which can lead to small cracks in plaster or another type of finishing. That movement can create air leaks that cause your building’s energy performance to suffer and potentially open the gateway for damp and mould to appear.

    Both products can be used for these wall/ceiling connections: Airtight White vapour control membrane can be applied with an airless paint spray device. Or Airtight White Brush can be applied by brush. If you don’t have an airless sprayer but would still wish to install Airtight White yourself, don’t worry, we have a roller version for you. It may take a bit longer, but it gets the job done.

    • Envelope penetrations

    Pipe and wire penetrations can be the downfall of any air tightness testing. Airtight White and Airtight White Brush are applied around objects that penetrate any surface to the external envelope, sealing where most tapes and membranes fail. 

    Before you apply Airtight White or Airtight White Brush, first apply polyurethane foam around any penetrations. After hardening, remove the excess foam and apply a generous amount of Airtight White Brush with a flat paintbrush. In all cases, apply a sufficient, well-covering layer to guarantee airtightness and a strong radon barrier and vapour control membrane.

    • Window/Door Reveals

    Airtight White can be applied (and is tested) on different construction materials such as concrete, brick, wood, PVC, aluminium and polyurethane foam. With a coat of Airtight White, the whole window/door reveal can be made airtight.

    Working method: cut off the excess polyurethane foam, and apply Airtight White Brush.

  • Data Sheets & Certificates
  • Architects Specification

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  • Delivery

    All delivery charges are included in the price of the products and are dependent on the products selected for purchase. This charge is based on delivery to mainland UK, excluding the Scottish Highlands & the Islands where additional shipping charges will apply. For more information read our delivery policy in full.

  • Returns

    We, at Intelligent Membranes, would like you to be 100% satisfied with your purchase and our service. In the unfortunate event of any item being unsuitable or wrong, please read our returns policy in full.

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