Passive Purple Retrofit - Retrofit Airtightness Spray/Roller Paint (10kg)
Passive Purple Retrofit - Retrofit Airtightness Spray/Roller Paint (10kg)
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Passive Purple Retrofit – Breathable Airtightness for Existing Buildings
Passive Purple Retrofit is a liquid-applied airtight membrane for older and solid-wall buildings that need to breathe. Sprayed or rolled on internally, it seals walls, ceilings 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?
| Passive Purple | Passive Purple Retrofit | |
|---|---|---|
| Vapour behaviour | Vapour control | Vapour open (breathable) |
| Best for | New builds and insulated build-ups – applied on the warm side of the insulation | Older, solid-wall and breathable buildings where moisture must be able to dry out |
| Airtight | Yes | Yes |
Not sure which you need? Our condensation risk analysis will tell you, or see Passive Purple for vapour control.
Key Benefits
- 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.
- Seamless: no tapes, laps or weak points – seals around pipes, cables and joists.
- Spray or roller: fast, even coverage on large walls and ceilings.
Where to Use It
- Solid brick and stone walls
- Lime-plastered walls
- Period and traditional homes
- Ceilings, junctions and service penetrations
- Timber-frame and mixed-construction retrofits
For joints, gaps and detailing, use Passive Purple Retrofit Brush, a fibre-reinforced brush grade.
Tested & Certified - fire-rated, watertight & breathable
Passive Purple Retrofit is a product of Passive Purple External, and all certification is that of Passive Purple External:
- Reaction to fire Euroclass B-s1,d0 (EN 13501-1, on A1 substrates ≥653 kg/m³) & ASTM E84 Class A (Flame Spread 0 / Smoke 15)
- Watertight Class W1 (EN 13859-2) & water permeability Class W3 (EN 1062-3); near-zero water absorption (EN 16302)
- Breathable / vapour-open — Sd ≈ 0.6 m (EN ISO 12572)
- Crack-bridging A3 (23°C) / A4 (-10°C) (EN 1062-7) & CO₂ / carbonation barrier Class C1 (EN 1062-6)
- UV-stable · low-emission EMICODE EC2 · anti-fungus (rating 0)
- Kiwa BDA Agrément (BAW-21-214-P-A-UK) · Passive House component (phB) · US ICC-ES AC212 water-resistive barrier
Related Guides
Helpful guides related to this product:
Quality assurance: Download the free Installation & QA Record sign-off sheet (IM-QA-07) for this product.
- Technical Data
- Data Sheets
- FAQ
Product Collection:Passive Purple
Colour:Purple
Usage:Internal & External
Application: Spray/Roller
Sizes:10kg
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
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.
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