Colour(s)White
white airtight paint that is brush applied airtight paint that has fibres in to span and large gaps to make any form of construction airtight
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A+ Certified BBA Certified
SKU: IM/00AWB10-1
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Airtight White Brush – Home Pack (6.9kg) – Vapour Control Paint – Brush Applied

$123.77

Product Collection: Passive Purple
Applied By: Brush
Colour: White
Size: 6.9kg
Certification: BS Fire Class C | EN 13501-1:2018, cl. 11
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Airtight White brush vapour control membrane is a much thicker airtight vapour control paint. It is the paintbrush applied version of Passive Purple Edition – Airtight White.

**FREE DELIVERY**

Passive Purple is a VOC-free water-based product. It’s completely free of any nasty chemicals or fumes. What’s more, as a water-based product, cleaning your paintbrushes is a smooth, no mess task.

With its fibre reinforced polymer technology, Passive Purple Brush can bridge gaps of up to 5mm. Ideally, you want the structure to have as little gaps in as possible to save time and cost on materials. once all connections, joints, boards and penetrations are complete and located, simply use a firm paint brush to fill and seal over the gaps and joints. this alone will reduce air leakage an enormous amount leaving your final spray coat ”if required” the icing on the cake. With a filler style technique and putty like consistency, Passive Purple Brush is extremely easy and fast to apply with no surface or area a problem.

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. A spray applied version is available however, 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.

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. This is where Airtight White comes into play and can be used for wall/ceiling connections. 

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  • Key Details

    Why Choose Passive Purple Airtight White Vapour Control Membrane?

    Passive Purple Airtight White is the smarter way to guarantee airtightness where traditional tapes and silicones fail. Its fibre-reinforced formula creates a tough, flexible vapour control layer that bonds permanently to surfaces — even in tricky junctions and damp conditions.

    Perfect for Problem Areas

    • 🪟 Windows & Doors – Airtight White seals entire reveals, stopping hidden air leaks where tapes often peel or fail.

    • 🧱 Connection Joints – Bridges larger gaps between wall panels and joints, flexing with natural building movement to maintain a secure seal.

    • 🏠 Walls & Ceilings – Provides a continuous airtight layer across perimeter junctions, applied by brush or spray.

    • 🪨 Slab Connections – Creates a durable barrier between slabs, panels, and walls to eliminate leakage points.

    • 🔌 Service Penetrations – Pipes, cables, and ducts are sealed with ease, tackling the areas where tapes and grommets are too awkward to install.

    The Cost-Effective Solution

    Unlike membranes and tapes that can peel, shrink, or lose adhesion over time, Airtight White stays firmly in place. It applies quickly, even on damp surfaces, saving on labour, rework, and long-term energy costs.

    👉 With BBA & Passivhaus certification, Class C fire resistance, and proven airtightness levels of 0.03 ACH, Passive Purple Airtight White is the fastest, most reliable airtight membrane for modern and retrofit projects.

  • Description

    Passive Purple Airtight White Brush – 6.9kg

    Passive Purple Airtight White Brush is a fibre-reinforced polymer emulsion applied by paintbrush to create a permanent liquid airtight vapour control membrane. Its smooth white finish makes it perfect for retrofits, detailing, and projects where the airtight layer is left exposed.

    Key Features & Benefits

    • ✅ BBA Certified & Passivhaus Certified – guaranteed airtightness and durability you can trust

    • ✅ M1 Class, VOC-Free – water-based, non-toxic, and safe for installers and the environment

    • ✅ Fire Class C Rated – safer than traditional membranes rated only Class E

    • ✅ Exceptional Airtightness – achieves 0.03 ACH, far beyond the Passivhaus requirement of 0.6 ACH

    • ✅ Universal Adhesion – bonds to concrete, brick, timber, plasterboard, OSB, steel, and more

    • ✅ Coverage Efficiency – 1kg covers 1m²; one operative can apply up to 300m² per day

    Where to Use Airtight White Brush

    • Floor, wall, and ceiling junctions

    • Window and door reveals

    • Service penetrations (pipes, ducts, cables)

    • Small retrofit airtightness projects

    • Any area where a white airtight coating is required on show

    👉 The 6.9kg Passive Purple Airtight White Brush is the fast, certified solution for creating airtight, durable, and visually clean airtight layers in both new builds and retrofit projects.

    Additional information

    Size

    5kg (Brush Only), 10kg (Roller or Spray)
    Application

    Spray/Roll
    Placement

    Internal
  • Uses

    Envelope Penetrations – Seal Where Tapes Fail

    Service penetrations are one of the biggest risks to airtightness. Pipes, cables, and ducts that pass through the building envelope are notoriously difficult to seal with tapes or membranes. Airtight White solves this with a permanent liquid seal that bonds directly to the substrate.

    • Step 1: Fill around the penetration with polyurethane foam.

    • Step 2: Once hardened, remove excess foam.

    • Step 3: Apply Airtight White Brush generously around the penetration for a seamless, flexible airtight seal.

    The result is long-term airtightness and vapour control, without the risk of tapes peeling, shrinking, or losing adhesion.

    Windows & Door Reveals – Stop Hidden Leaks

    Windows and doors are notorious air leakage points. Airtight White is tested and proven on multiple substrates including concrete, brick, timber, PVC, aluminium, and polyurethane foam. A single coat creates a continuous vapour control layer, eliminating leaks and improving building performance.

    Simply trim excess polyurethane foam and apply Airtight White Brush for a durable, airtight finish that won’t crack, peel, or come unstuck like traditional silicones.

    👉 From floor junctions to curtain walls, Passive Purple Airtight White ensures every detail of your building envelope is fully sealed, delivering certified airtightness for both retrofit and new build projects.

  • Data Sheets & Certificates
    Technical Data Sheet
    BBA Certificate - Brush
    Passive Purple Brush Safety Data Sheet
    Install Guide
  • 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.

    Intelligent Membranes do not offer a next day delivery service.

    Intelligent Membranes aim for deliveries to be with the customer within 2 working days. During the festive period deliveries could take longer.

    Orders placed before 12pm will be dispatched the same day, any orders placed after 12pm will be dispatched the following working day

  • 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.

Airtight White Brush – FAQs

❓ What is Airtight White Brush?

Airtight White Brush is a fibre-reinforced, liquid-applied vapour control membrane designed to be applied with a standard paintbrush. It creates a durable airtight barrier in detail areas, junctions, and retrofits where spray or roll application isn’t practical.

❓ Where can I use Airtight White Brush?

It’s ideal for sealing:

  • Floor-to-wall and wall-to-ceiling junctions

  • Window and door reveals

  • Around service penetrations (pipes, ducts, cables)

  • Small joints and tricky detail work

  • Retrofit projects where airtightness needs to be applied in tight spaces

❓ What surfaces does Airtight White Brush adhere to?

Airtight White Brush bonds securely to a wide range of substrates, including:

  • Concrete and blockwork

  • Brick

  • Timber and OSB

  • Plasterboard

  • Steel

  • PVC and aluminium

  • Polyurethane foam

❓ How much coverage does Airtight White Brush provide?

Coverage is approximately 1m² per kg. A 6.9kg tub will cover around 6.9m², depending on surface condition and thickness applied.

❓ Is Airtight White Brush certified?

Yes — Airtight White Brush is BBA Certified, independently tested for performance and durability.

❓ How airtight is Airtight White Brush?

It delivers exceptional airtightness, with test results as low as 0.03 air changes per hour (ACH) when used correctly. This makes it suitable for projects targeting very low energy performance standards.

❓ Is Airtight White Brush safe to use indoors?

Yes — it is a VOC-free, water-based product rated M1 Class. It contains no harmful chemicals, making it safe for both the installer and the building’s occupants.

❓ Does Airtight White Brush have fire resistance?

Yes — it is rated Fire Class C, offering higher fire protection compared to traditional tapes and membranes that are typically only rated Class E.

❓ Why choose Airtight White Brush over tapes or foils?

Unlike tapes and membranes, which can peel, shrink, or lose adhesion, Airtight White Brush forms a permanent liquid bond to the substrate. It’s faster to apply, adapts to damp conditions, and gives long-term airtightness without the risk of failure.

👉 Still have questions? Contact our team at info@intelligentmembranes.com for tailored advice on how Airtight White Brush can help your airtightness project.

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