Passive Purple Retrofit - Retrofit Airtightness Brush Applied Paint (5kg)

Passive Purple Retrofit Brush – Breathable Airtightness for Existing Buildings

Passive Purple Retrofit Brush is a fibre-reinforced, liquid-applied airtight membrane for older and solid-wall buildings that need to breathe. Brushed on internally, it seals joints, gaps, cracks and junctions against draughts and air leakage while staying vapour open (Sd ≈ 0.6 m), so moisture in the wall can still dry out.

Why Do Older Buildings Need a Breathable Airtight Layer?

Solid brick, stone and lime-plastered walls were built to manage moisture by letting it move through the wall and dry out. Sealing them with a vapour-tight layer can trap that moisture in the fabric, leading to damp, mould and decay.

Passive Purple Retrofit stops the air leaks that cause heat loss and draughts, but still lets water vapour pass through – so the wall keeps working the way it was designed to.

Passive Purple or Passive Purple Retrofit?

Not sure which you need? Our condensation risk analysis will tell you, or see Passive Purple for vapour control.

Key Benefits

• Fibre-reinforced: spans larger joints and gaps for reliable detailing.
• Airtight & smoke-tight: stops draughts and uncontrolled air leakage.
• Breathable: vapour open (Sd ≈ 0.6 m) so walls can keep drying out.
• Crack-bridging: stays sealed as older buildings move.
• Anti-fungus: resists mould growth on the coating.
• Low emission: EMICODE EC2 rated.
• Fire-rated: Euroclass B-s1,d0.
• Brush applied: no specialist equipment – ideal for smaller rooms, detailing and DIY retrofits.

Where to Use It

• Joints, gaps and cracks in older walls
• Junctions around windows, doors, floors and ceilings
• Pipe, cable and joist penetrations
• Solid brick, stone and lime-plastered walls
• Smaller rooms and period homes

For large walls and ceilings, use Passive Purple Retrofit Spray/Roller (10kg) for faster coverage.

Quality assurance: Download the free Installation & QA Record sign-off sheet (IM-QA-07) for this product.