Airtight White Brush - Home Pack (6.9kg) - Vapour Control Paint - Brush Applied

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.

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.

Product Collection: Passive Purple
Applied By:Brush
Colour: White
Size:6.9kg
Certification:BS Fire Class C | EN 13501-1:2018, cl. 11

Technical Data Sheet

BBA Certificate - Brush

Passive Purple Brush Safety Data Sheet

Install Guide

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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