Leak-proofing paint PASSIVE PURPLE®

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What is Passive Purple and how it works
Passive Purple is the world’s first Passivhaus‑certified liquid vapour control, airtight and smoke‑tight paint. Applied by spray or roller to the warm side of insulation, it forms a continuous vapour control, airtight and smoke barrier across the building envelope, preventing unintended air leakage through walls, floors, roofs and junctions. Suitable for new build and retrofit projects seeking high airtightness and Passivhaus performance.

Why use a liquid airtight paint?
Uncontrolled air leakage causes heat loss, condensation and mould. Building materials move, creating micro‑cracks and hidden leakage paths. A liquid airtight membrane provides a flexible, durable continuous layer that accommodates movement in the fabric and ensures long‑term protection against draughts and damp.

Application methods — spray, roller or brush

• Spray application: Using an airless machine or roller, one installer can apply up to ~300 m²/day, offering a fast airtightness solution for large areas.
• Brush application (Passive Purple Brush): A fibre‑reinforced variant for sealing junctions, penetrations and cracks (2–5 mm) and for smaller retrofit or domestic projects.

Suitability
Compatible with all common construction types: new build, retrofit, traditional masonry and Light Gauge Steel (LGS). Bonds to brick, block, timber, concrete, plasterboard, OSB and steel.

Key benefits

• Passivhaus certified for verified performance
• Continuous, flexible membrane with no weak overlaps
• Retrofit friendly — can be applied internally without removing finishes
• Water‑based, low VOC — suitable for indoor use
• Permanently airtight once cured — can be plastered, rendered or painted

Airtightness — explanation

• What is airtightness? The control of unintended air flow through the building fabric.
• How to achieve it? By creating a continuous airtight barrier; liquid membranes are one of the most effective methods.
• Relevant standards: UK new builds ≤10 m³/h·m² @ 50 Pa; Passivhaus ≤0.6 ACH.
• Why it matters: Reduces energy loss, improves comfort, prevents condensation and supports healthy indoor air quality.

Passive Purple and Passivhaus

• Supports Passivhaus principles: airtightness, high levels of insulation, thermal‑bridge free detailing and ventilation with heat recovery.
• Widely used in retrofit and new‑build projects across Europe and the UK to meet certification targets.

Preparation and priming
Surface preparation is essential. Prime dusty, porous or lime substrates with Lime Prime; use Primer I.M for dense, sealed or aged substrates to consolidate. After curing, prime with Supergrip for reliable plaster or adhesive bonding.

Tested and certified
Passive Purple is independently verified to ASTM (ICC‑ES) and EN standards. Selected performance data and certifications:

• French A+ indoor‑air rating & Finnish M1 — very low VOC emissions (EN 16516 / RTS)
• Passive House Institute Class A airtight — 0.02 m³/h·m² @ 50 Pa (EN 12114)
• Air barrier material — 0.02 L/s·m² at 75 Pa (ASTM E2178)
• Reaction to fire — ASTM E84 Class A (Flame Spread 0); EN 13501‑1 Euroclass C‑s1,d0 (B‑s1,d0 with FRED)
• Watertight (EN 14891) & intelligent vapour control Sd ~0.8–40 m (EN ISO 12572)
• Solar Reflectance Index 52 — reflects ~45% of solar energy (ASTM E1980)
• Radon barrier — diffusion coefficient 3.3 × 10⁻¹² m²/s (ISO/TS 11665‑13)
• Methane / ground‑gas barrier — low permeability (ISO 15105)
• Strong adhesion — steel 2.7, CLT 1.83, gypsum 1.6, brick 1.5 N/mm² (EN ISO 4624)
• Flexible & crack‑bridging — ~219–350% elongation (EN 12311‑1)
• 10/10 mould resistance — no defacement (ASTM D3273)
• Environmental Product Declaration (EN 15804); ICC‑ES ESR‑4715; BBA approved; Passivhaus certified

Typical uses
Creates a continuous airtight and vapour‑control layer across challenging details: concrete, brick and blockwork, timber and OSB, floor‑to‑wall and wall‑to‑ceiling junctions, vertical and horizontal joints. Also used as a radon barrier and intelligent vapour control in both retrofit and new build projects.

Related documentation

• Passive Purple: Tested & Certified (ICC‑ES, ASTM & EN data)
• Passive House Institute Class A airtight (EN 12114)
• French A+ indoor‑air rating
• Liquid airtight membranes vs parge coating
• What is a vapour control layer? — VCL explained

Quality assurance
Installation guidance and QA resources are available for specifiers and installers, including an Installation & QA Record sign‑off sheet for the product.

Technical data / specifications

• Product name: Passive Purple®
• Product collection: Passive Purple Intelligent Membrane
• Pack size / reference shown: 11.4 kg
• Application: Spray or Roll (fibre‑reinforced brush product available for details/repairs)
• Colour: Purple
• Coverage (practical): up to ~300 m² per installer per day by spray (depends on substrate and thickness)
• Rule of thumb: 1 tin brush = 5 tins spray (approx.)
• Key certifications: Passive House Institute Class A airtight; BBA; ICC‑ES ESR‑4715; French A+ and Finnish M1 emissions; EPD (EN 15804)
• Air barrier performance: 0.02 L/s·m² at 75 Pa (ASTM E2178)
• Airtightness achieved in testing: 0.02 m³/h·m² @ 50 Pa (EN 12114)
• Reaction to fire: ASTM E84 Class A; EN 13501‑1 Euroclass C‑s1,d0 (B‑s1,d0 with FRED)
• Watertight: EN 14891 compliant
• Vapour control (intelligent): Sd ~0.8–40 m (EN ISO 12572)
• Radon diffusion coefficient: 3.3 × 10⁻¹² m²/s (ISO/TS 11665‑13)
• Methane / ground‑gas: low permeability (ISO 15105)
• Adhesion (EN ISO 4624): steel 2.7 N/mm²; CLT 1.83 N/mm²; gypsum 1.6 N/mm²; brick 1.5 N/mm²
• Elongation / flexibility: ~219–350% (EN 12311‑1)
• Mould resistance: ASTM D3273 — 10/10 no defacement