Finishing paint PASSIVE PURPLE

liquidwater-basedfor concrete

What is Passive Purple and How Does it Work?
Passive Purple® is a high-performance, liquid-applied airtight, vapour control and smoke-tight membrane. It is spray or roller applied to form a seamless, continuous vapour control, airtight and smoke tight layer across the building envelope. Applied to the warm side of insulation, it prevents air leakage through walls, floors, roofs and junctions, and is suitable for new builds and retrofit airtightness projects.

Why Liquid Airtight Paint?
Liquid airtight paint creates a flexible, durable airtight layer that adapts to movement in the building fabric, sealing micro-cracks and hidden leakage points that lead to heat loss, condensation and mould. It delivers long-term protection against draughts and damp and supports achieving stringent airtightness standards.

Application Methods

• Spray application: Using an airless machine or roller, one installer can apply up to 300m² per day, making it a fast airtightness solution.
• Brush application (Passive Purple Brush): Fibre-reinforced version ideal for sealing junctions, penetrations and cracks (2–5 mm), and for smaller projects and retrofits.

Suitability
Suitable for all types of building construction: new builds, retrofits, traditional build, Light Gauge Steel (LGS). Works on brick, block, timber, concrete, plasterboard, OSB and steel.

Key Benefits

• Passivhaus certified for guaranteed performance.
• Seamless and flexible — no weak points or overlaps.
• Retrofit ready — can be applied internally without removing walls.
• Water-based and low VOC — safe for indoor use.
• Permanent airtight layer — can be plastered, rendered or painted once cured.

Airtightness — explained

• What is airtightness? Controlling unintended air leakage through the building fabric.
• How is airtightness achieved? By creating a continuous airtight barrier; liquid airtight membranes are a best-practice approach.
• UK airtightness standards: New builds ≤10 m³/h·m² @ 50 Pa; Passivhaus requires ≤0.6 ACH.

Preparation & Priming
On bare, dusty, porous or lime substrates prime first with a suitable primer; on dense or sealed substrates use a consolidating primer. Once Passive Purple has cured, prime with a suitable primer so plaster and dot-and-dab bond firmly.

Tested & Certified — worldwide
Passive Purple is verified to both ASTM (ICC-ES) and EN standards and includes the following verified properties and certifications:

• French A+ indoor-air rating & Finnish M1 class — 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 — Class A to ASTM E84 (Flame Spread 0); Euroclass C-s1,d0 to EN 13501-1 (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, Passivhaus certified & BBA approved.

Related usage notes
Designed for use as an internal vapour control and airtight layer; suitable for spray, roller or brush systems to provide a complete airtight solution from large surface areas to small details.

Characteristics / technical specifications

• Formulation: water-based, low VOC liquid-applied membrane.
• Typical pack size shown on page: 11.4 kg (product presented in this pack size).
• Application methods: airless spray, roller, brush (fibre-reinforced brush product available for details).
• Curing: forms a permanent, flexible layer that can be plastered/painted/rendered once cured.
• Elongation (crack-bridging): ≈ 219–350% (EN 12311-1).
• Adhesion (EN ISO 4624): steel 2.7 N/mm²; CLT 1.83 N/mm²; gypsum 1.6 N/mm²; brick 1.5 N/mm².
• Airtightness performance: 0.02 m³/h·m² @ 50 Pa (Passive House Institute Class A).
• Air barrier (ASTM E2178): 0.02 L/s·m² at 75 Pa.
• Fire reaction: ASTM E84 Class A; EN 13501-1 Euroclass C-s1,d0 (B-s1,d0 with FRED product).
• Vapour control range: Sd ≈ 0.8–40 m (EN ISO 12572).
• Radon diffusion coefficient: 3.3 × 10⁻¹² m²/s (ISO/TS 11665-13).
• Mould resistance: 10/10 (ASTM D3273).
• Certifications: Passivhaus certified, ICC-ES ESR-4715, BBA approval, French A+ and Finnish M1 indoor-air ratings, EPD (EN 15804).