Passive Purple External Airtight Fire Rated Façade Waterproofing Membrane (10kg) - White Spray / Roller

£103.99 GBP

~~£129.99 GBP~~ £103.99 GBP

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Excelling Characteristics of Passive Purple External

Passive Purple External is the world’s first and only Fire Class B liquid-applied airtight paint, offering unmatched performance for both internal and external applications. It combines airtightness, weather protection, and intelligent moisture management in a single certified solution.

Key Benefits & Features

🔥 Fire Class B – exceptional fire resistance, setting it apart from standard membranes.
🌧 Raintight & Vapour Breathable – keeps water out while allowing moisture to escape, ensuring a healthy building fabric.
🔒 Airtight & Smoke-Tight – delivers a complete barrier to uncontrolled air leakage and smoke movement.
☀️ UV Resistant & Self-Cleaning – long-term durability with reduced dirt pickup and surface staining.
🦠 Anti-Fungus Protection – prevents mould growth and safeguards indoor air quality.
🧱 Crack-Bridging – maintains airtightness even where movement or minor cracks occur.
🧪 Concrete Protection – blocks carbonation, provides realkalisation, and shields against salts from roads and de-icing.
🌍 Dual Purpose – suitable for internal and external applications across retrofit and new-build projects.
💨 Intelligent Moisture Management – allows the substrate to breathe, balancing vapour openness with airtight performance.

👉 With Passive Purple External, you get airtightness, weather resistance, and long-term structural protection in one advanced, certified liquid membrane — ideal for timber frame, retrofit, and high-performance construction projects.

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Why Choose Passive Purple External?

Passive Purple External is the ultimate airtight and weatherproof vapour control paint, engineered for high-performance building envelopes. Whether for retrofit or new build projects, it delivers unbeatable protection, speed of application, and long-term durability.

Key Benefits

Cost Effective – A single installer can cover up to 300m² per day using an airless spray device. That means faster application, reduced labour costs, and quicker project delivery.
VOC-Free & Eco-Friendly – Water-based and completely VOC-free, making it safe for applicators, building occupants, and the environment.
Flexible Application – Apply with an airless spray machine for large projects or a roller for smaller areas and touch-ups.
External Protection – Creates a tough, watertight airtight membrane on external facades, providing UV resistance and long-term weatherproofing.
Fire Rated – Certified Class B fire resistance, outperforming standard membranes and coatings for safety and compliance.
Breathable Airtightness – Intelligent design ensures buildings stay airtight and smoke-tight, while still allowing vapour to escape where needed.
KIWA Approved – Independently tested and certified for performance, giving you confidence on every project.

With airtightness, fire safety, weather protection, and breathability combined in one product, Passive Purple External is the smart choice for architects, builders, and retrofit specialists who want certified performance without compromise

Substrates & Compatibility

Passive Purple External is designed for maximum versatility and can adhere to virtually any form of construction, including:

Concrete and brick walls
Engineered timber panels / OSB panels
Insulation boards and panels
Fibre cement boards

This makes it the ideal solution for both new build and retrofit projects, across residential, commercial, and industrial applications.

Directions for Use

For best results, follow these application guidelines:

Surface Preparation

Remove salt efflorescence, dust, loose materials, and standing water.
Apply only on a closed surface – fill holes and joints first with a fast-setting cement-based product or polyurethane foam.

Application Conditions

Substrate temperature: above 5°C.
Application on humid surfaces is permitted, but standing water must be removed.
Do not add water or solvents.
Do not apply in direct full sunlight or during rain.

Application Method

Apply using an airless spray device (e.g., Graco) or with a paint roller.
Always apply two coats. Allow the first layer to dry fully before applying the second.
Clean all tools immediately with water after use.

Usage:External or Internal
Applied By:Roller or Spray
Colour:Purple, Black,Cream or White
Size:10kg
Certification:BS Fire Class B|ASTM Fire Class A

Technical Data Sheet (TDS)

Safety Data Sheet

Install Guide

Kiwa Agrement

Safety Data Sheet (SDS)

3D Images

Passivhaus Institut Certificate 2025

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.

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.