VARA FLUID Brush – Fluid applied membrane

Paint-on Airtight, Smart Vapour Control Layer

Partel VARA FLUID Brush is a humidity variable air and vapour control layer (AVCL) engineered to provide superior airtightness for long-term performance of the building envelope.

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VARA FLUID Brush is a water-based air & vapour control layer (AVCL) that can be brushed, providing a continuous airtightness over cracks and gaps in both new build and retrofit projects. Advanced Hygrovariable Technology allows incredible summer drying conditions, but can equally protect the construction in winter.

  • Innovative liquid airtight membrane that changes vapour permeability according to the ambient relative humidity (RH). This contributes to maximum protection in the building envelope where moisture levels are critical, allowing vapour to escape and dry the structure.
  • Ensures optimum moisture flow through building structures with a Sd range of 0.15m to 16m
  • Hygrovariable Technology – Extremely safe airtight system
  • phA Class Passive House Certified airtight system, featuring an air permeance value of 0.00 m³/(m²h)
  •  Flexible – ensures adequate coverage (cracks and joints up to 2 mm)
  • LOW VOC polymer-based liquid
  • Class W1 resistance to water penetration
  • Excellent adhesion on various surfaces
  • Fast application – speeds up construction, especially for commercial projects
  • Single component, ready-to-use product


VARA FLUID Brush is an air and vapour control layer designed for use internally and externally on the warm side of insulation on wall, ceiling, roof and floor applications. It is easily applied, vertically or horizontally, with a paintbrush and dries to an airtight flexible coating.

Suitable for:

  • Application on various surfaces – masonry concrete, silicate, OSB, plywood etc.
  • Wall, ceiling, roof and floor applications
  • Externally vapour open and vapour closed structures
  • Wall to floor connections
  • Wall to ceiling connections
  • Wall to timber connections
  • General construction joints
  • Residential and commercial buildings

VARA FLUID Brush can be applied to damp surfaces and is ready to use. VARA FLUID is beige when applied and turns dark beige when dried. The liquid membrane can be applied directly to the substrate after the building surface has been properly prepared. The cracks should be filled first. We recommend VARA FLUID be applied in two layers. For further information, please consult the Technical Data Sheet.

Product Content: 5.5 kg

Technical Data

Sd VAPOUR VARIABILITY RANGE 0.15-16 @ 0.3mm EN ISO 12572