Protective coating PASSIVE PURPLE BRUSH

for the building industryliquid

Product overview
Passive Purple is a liquid airtight vapour control membrane designed for application on the warm side of insulation across the building envelope. The Brush Pack is the thicker, brush-applied variant intended for smaller projects, detail work and sealing small holes and joints. The product is BBA approved, Passivhaus certified, ICC tested, provides radon barrier protection and is M1 class VOC-free.

Key points

• BBA approved & Passivhaus certified liquid airtight vapour control layer
• Radon barrier protection
• M1 class, VOC-free, water‑based formulation
• Fire rating: Class C
• Passivhaus tested example: 0.03 ach; supports achieving ≤ 0.6 ACH in suitable builds
• Smoke tight
• ICC tested and certified
• Coverage (brush): ~1 kg per 1 m² (indicative)

Application & preparation

• Applicable to floors, walls, roofs, joists and complex junctions (warm side of insulation).
• Surfaces must be solid, dust-free and closed prior to application.
• A closed surface requires all holes and joints to be sealed before coating:
• Large holes and joints (>5 mm): seal with fast-setting cementitious products or polyurethane foam.
• Small holes and joints (2–5 mm): seal directly using Passive Purple Brush (thicker brush-applied version).
• For large projects, Passive Purple can be spray-applied with an airless machine (single operator productivity up to 300 m²/day).
• For smaller projects, the Brush Pack is applied with a flat paintbrush; a roller-applied variant is available where no airless sprayer is used.
• Wall-to-ceiling interfaces and junctions between different materials must be made airtight.

Uses and suitable substrates

• Suitable on concrete, brick, blockwork, timber and many common substrates.
• Used for floor/wall connections, ceiling connections, vertical and horizontal joints, wall penetrations and airtight detailing.
• Appropriate for both retrofit and new-build applications.

Related guides

• My Builder Forgot the Vapour Control Layer? Here’s How to Fix It
• What Is a Vapour Control Layer? | VCL Explained
• How to Retrofit Vapour Control Without the Mess (BBA approved / Passivhaus certified)

Characteristics / technical specifications

• Product collection: Passive Purple
• Commercial denomination (model): Passive Purple Brush Pack
• Applied by: Brush (brush-applied version); spray and roller options available for other Passive Purple variants
• Colour: Purple
• Coverage (brush reference): ~1 kg per 1 m² (indicative)
• Spray application productivity: up to 300 m²/day (single operator, airless)
• Certifications: BBA approved, Passivhaus certified, ICC tested
• Performance example: Passivhaus test 0.03 ach; supports ≤ 0.6 ACH in appropriate builds
• VOC / Emissions: M1 class, VOC-free, water-based
• Fire rating: Class C
• Functions: Airtight vapour control layer, radon barrier, smoke tight
• Suitable for: New builds and retrofits; warm side of insulation application