Passive Purple is more than just a paint – it’s the world’s most advanced airtight membrane. Designed and certified for Passivhaus projects, it delivers seamless vapour control and long-term airtightness without the need for tapes or complex detailing. Applied like a standard paint, Passive Purple creates a flexible yet durable barrier that improves building performance and reduces energy loss.
Whether you’re working on a new build, retrofit, or heritage project, Passive Purple offers a faster, cleaner and more reliable way to achieve airtightness. Its unique liquid-applied formula ensures full coverage around tricky details, pipes and penetrations – guaranteeing compliance and performance that traditional membranes can’t match.
Which products in our collections ARE OUR Intelligent Membrane?
Our Intelligent Membrane Products
Within our range, the products that define our Intelligent Membrane technology are Passive Purple Internal and Passive Purple External. These advanced liquid-applied membranes deliver exceptional airtightness and vapour control, while still allowing the building fabric to breathe. Designed for both new builds and retrofit projects, they provide a seamless, durable barrier that enhances energy efficiency and long-term building performance.
Passive Purple Internal – Our Intelligent Membrane for Vapour Control
Passive Purple Internal is a high-performance intelligent membrane paint, designed to provide superior vapour control on the inside of a building. Applied to walls, ceilings, and connecting joints, it creates a continuous airtight layer that significantly reduces air leakage and boosts overall energy efficiency ratings.
What makes Passive Purple Internal truly intelligent is its unique formulation — it actively responds to changes in temperature and humidity, helping to prevent dampness and mould while maintaining a healthy indoor environment.
It can be applied quickly and efficiently using an airless sprayer or roller, with a specialist brush edition available for smaller or detailed areas such as connecting joints. The result is a seamless, durable barrier that enhances both comfort and building performance.
Passive Purple External – Our Intelligent Membrane for Airtightness and Breathability
Passive Purple External is our advanced intelligent membrane paint, engineered to deliver exceptional airtightness on the exterior of a building while remaining fully vapour-open. This means it protects against unwanted air leakage and moisture ingress, yet still allows the building fabric to breathe — making it ideal for both new builds and retrofit projects.
Thanks to its unique formulation, Passive Purple External adapts to changes in temperature and humidity, providing lasting protection against dampness, mould, and weather-related damage. It also meets the world’s most stringent performance standards, including Passive House certification.
Application is fast and efficient via airless sprayer or roller, with a brush version available for precision work around penetrations, junctions, and detail areas. The result is a seamless, durable weather barrier that enhances energy efficiency and long-term building health.
🔹 FAQ Section
What is Passive Purple airtight paint?
Passive Purple is a liquid-applied airtight membrane that replaces tapes and sheets, offering seamless airtightness with no joins, gaps, or weak points. It also has anti-mould properties, protecting indoor environments from damp-related issues.
Is Passive Purple Passivhaus certified?
Yes – it is the world’s first airtight paint to achieve official Passive House certification, proving its performance and reliability in high-standard construction.
Can Passive Purple be used internally and externally?
Yes – Passive Purple Internal and Passive Purple External are designed for different applications, making the system suitable for both new builds and retrofits.
How does Passive Purple compare to tapes or membranes?
Unlike tapes or sheet membranes, Passive Purple creates a seamless, continuous airtight barrier. This eliminates the risk of failure at joints and ensures long-term airtightness while also resisting mould growth.
What is the difference between Passive Purple Internal and Passive Purple External?
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Passive Purple Internal is applied to the warm side of the insulation to provide internal airtightness. It seals gaps within the building envelope to maintain indoor comfort, prevent drafts, and improve energy efficiency. Its anti-mould formulation prevents condensation-related mould growth on the inside of walls and ceilings.
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Passive Purple External focuses on external airtightness, sealing the outer shell of the building to stop uncontrolled airflow, minimise moisture ingress, protect the structure, and reduce heat loss.
Importantly, Passive Purple External can also be applied internally in retrofit projects (e.g., solid wall builds) where extra breathability is needed, making it versatile for heritage and retrofit applications.
Why are our products called “The Intelligent Membrane”?
Passive Purple Internal and Passive Purple External are known as Intelligent Membranes because they adapt to the building’s environment, providing optimum performance.
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Responsive Protection – Reacts to humidity and temperature changes, guarding against damp and mould.
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Enhanced Efficiency – Reduces air leakage while allowing controlled breathability.
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Adaptive Performance – Provides extra waterproofing and moisture protection under harsh conditions.
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Efficient Installation – Spray, roll, or brush application ensures fast, full coverage around joints, gaps, and complex details.
We are proud to manufacture and supply these unique intelligent membrane products. Their distinctive purple colour has become a symbol of eco-friendly innovation and performance in the global construction industry.
Passive Purple Editions
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Passivhaus Airtight Sealant – 600ml
Enquire Now Below From £12.00 + VAT Select options This product has multiple variants. The options may be chosen on the product page
