• Passive Purple brush applied airtight paint that has fibres in to span and large gaps to make any form of construction airtight
  • Airtight paint for masonry builds that is brush applied
  • liquid airtight paint that is brush applied to seal wall penetrations like water pipes
  • Retrofit airtight paint – Passive Purple applied for improved energy efficiency and airtightness in existing buildings
  • service pipe airtight paint that is brush applied to make an airtight seal
  • airtight paint for joist ends on timber frame or masonry builds
  • airtight paint for joints on OSB timber frame
  • paint brush applied Airtight liquid vapour control
  • Passivhaus certified airtight paint
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Passive Purple Brush - Airtight Paint 6.9KG

Passive Purple Brush - Airtight Paint 6.9KG

£59.99 GBP
£90.00 GBP £59.99 GBP
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What is Passive Purple Brush?

Passive Purple Brush is a fibre-reinforced, liquid-applied airtight membrane designed for detailed airtightness work. Applied with a simple paintbrush, it creates a permanent, seamless vapour-control layer that seals tricky gaps and penetrations where spraying or rolling is difficult.

Where is it used?

Passive Purple Brush is ideal for:

  • Service penetrations (pipes, cables, ducts)
  • Window and door frames
  • Floor-to-wall and wall-to-ceiling junctions
  • Cracks and gaps up to 5mm
  • Touch-ups after air testing or snagging

Why use the Brush version?

Unlike spray-applied Passive Purple, the Brush version contains fibres that span and seal larger cracks and irregularities. This makes it the go-to airtight paint for precision work, detailing, and repairs, while still delivering the same Passivhaus-certified airtightness as the main system.

Surface preparation

  • Ensure surfaces are solid, dust-free, and closed.
  • Large gaps (>5mm): Fill with cement-based filler or foam before application.
  • Small to medium gaps (2–5mm): Passive Purple Brush can be applied directly.

Application & coverage

  • Applied with a flat paintbrush.
  • Easy to use for small projects and detailed work.
  • Once cured, it can be painted, plastered, or rendered over.

Why airtightness matters

Air leakage through cracks and junctions:

  • Reduces energy efficiency
  • Allows draughts, damp, and mould
  • Can compromise Passivhaus and building regulations compliance

By sealing with Passive Purple Brush, you ensure every junction is airtight, securing energy performance and long-term building health.
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  • Details
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  • Technical Data
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Passive Purple Brush – Airtight Detailing Made Simple

Passive Purple Brush is a fiber-reinforced liquid airtight membrane designed for the details that make or break airtightness. Where tapes, foils, or sprays struggle, Passive Purple Brush delivers a seamless, flexible, Passivhaus-certified seal that protects your building’s energy performance for life.

Why choose Passive Purple Brush?

  • Passivhaus certified airtight paint for guaranteed performance
  • Fibre-reinforced formula bridges cracks and gaps up to 5mm
  • Precision solution for windows, doors, service penetrations, and junctions
  • Ideal for retrofits and new builds – works across masonry, timber, plasterboard, OSB, and concrete
  • Water-based, low VOC, safe indoors
  • Permanent airtight layer – can be plastered, painted, or rendered over once cured

Built for airtightness

Tiny cracks and junction leaks are one of the biggest causes of heat loss, damp, and mould. Passive Purple Brush eliminates these weak spots, ensuring airtight continuity across the building envelope. Whether in a Passivhaus project or a retrofit upgrade, it gives you the confidence of an airtight seal without the hassle of tapes or grommets.

Contact our team at info@intelligentmembranes.com to find out how Passive Purple Brush can transform your airtightness strategy and help you meet UK airtightness standards and Passivhaus requirements.

Passive Purple Brush Uses

Airtight flexible coating that has excellent adhesion on different surfaces such as:

  • Concrete
  • Brick
  • Wood
  • Floor/wall connections
  • Ceiling connections
  • Vertical and horizontal joints

Product Collection: Passive Purple
Applied By:Brush
Colour:Purple

Key Points:

Vapour control layer
Passivhaus certified
Airtight easy to use paint brush applied
Great for retrofit and new builds
Smoke Tight
ICC tested and Certified
BBA approved and Certified
1kg will cover 1m2

Technical Data Sheet

Install Guide

Safety Data Sheet

BBA Certificate - Brush

At Intelligent Membranes, we help architects, contractors, retrofitters and self-builders achieve airtightness and waterproofing targets with liquid-applied systems. Our flagship airtight system, Passive Purple®, is airtight at all times yet breathable when the building fabric needs to release vapour — we call this intelligent breathability.

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Shipping & returns summary

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 the following for advice on returning goods to us.

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Watch Passive Purple Brush - Airtight Paint 6.9KG in Action