Preparation paint

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Product overview
Passive Purple Preparation Pack contains membranes, tapes and sealants required to prepare substrates before applying a liquid airtight vapour control layer, ensuring correct adhesion and continuous airtightness across building envelope junctions.

What is and how to use Passive Purple?

• Passive Purple is an intelligent liquid airtight vapour control membrane applied with an airless spray to the warm side of the insulation across floors, walls, roofs and joists, including complex junctions.
• When applied on the warm side, it forms a continuous vapour control layer (VCL) and can be used on either face of the external envelope as required by the design.
• Surfaces must be solid, dust‑free and closed before application.
• Closed surfaces mean all holes and joints are sealed prior to coating:
• Large holes and joints (>5 mm): seal with fast‑setting cementitious products or polyurethane foam.
• Small holes and joints (2–5 mm): seal with Passive Purple Liquid Brush (brush‑applied, thicker version).
• After preparation, Passive Purple can be spray‑applied; a single installer can cover up to 300 m² per day with an airless sprayer.
• For smaller projects (eg. private houses), Passive Purple Brush can be applied with a flat paintbrush.
• Ensure airtightness at wall‑to‑ceiling and material transition connections (brick‑to‑concrete, steel‑to‑concrete, etc.).
• Different materials react differently to humidity and temperature changes and may cause small cracks that create air leakage, reduced energy performance and risk of damp and mould.

Note
If an airless sprayer is not available, a roller‑applied version is available; application may take longer but still provides reliable airtight performance.

Related guides (titles)

• My Builder Forgot the Vapour Control Layer? Here’s How to Fix It
• What Is a Vapour Control Layer? | VCL Explained
• How to Retrofit Vapour Control Without the Mess

Why choose Passive Purple?

• BBA Certified & Passivhaus Certified: certified liquid airtight vapour control layer suitable for high‑performance projects.
• Radon barrier: provides radon protection where required.
• Application rate: up to 300 m² coverage per day for a single installer using an airless spray device.
• M1 Class, VOC‑free: water‑based, low‑emission product.
• Fire Class C: rated Fire Class C.
• Airtight performance: Passivhaus certified 0.03 ACH and can guarantee 0.6 ACH or under when installed correctly.

Passive Purple uses

• Adheres to common substrates including concrete, brick and wood.
• Used at floor/wall connections, ceiling connections and at vertical and horizontal joints.
• Also functions as a radon barrier where specified.

Pack contents (summary)

• Preparation pack includes membranes, tapes and sealants to create a complete airtight seal at junctions and penetrations.

Application methods

• Airless spray (recommended for speed and uniform coverage).
• Brush (Passive Purple Brush) for small holes, joints and smaller projects.
• Roller version available for installations without an airless sprayer.

Technical specifications

• Certifications: BBA Certified; Passivhaus Certified.
• Radon protection: suitable as a radon barrier.
• Coverage rate: up to 300 m² per day per installer with an airless sprayer.
• Product class: M1 class, VOC‑free water‑based product.
• Fire rating: Fire Class C.
• Airtightness performance: Passivhaus certified 0.03 ACH; can guarantee 0.6 ACH or under.
• Suitable substrates: concrete, brick, wood and typical envelope junctions (floor/wall, ceiling connections, vertical/horizontal joints).
• Application methods: airless spray, brush (Passive Purple Brush), roller (available).
• Pack: contains membranes, tapes and sealants for airtight preparation.
• Packaging/price note: sold as a preparation pack; price excludes VAT.