Everflex VBS Water-based Epoxy Primer

For sealing green concrete, priming damp substrates, or blocking rising damp, Everflex VBS Water-based Epoxy Primer provides a high-density moisture barrier. This two-part water-based epoxy controls negative hydrostatic pressure up to a 25-metre head of water, preventing moisture migration from destroying timber flooring, polyurethane membranes, and floor coatings.

How it works

Everflex VBS forms a low-permeability barrier that blocks water vapour and liquid water pressure from the negative side of the substrate. Once fully cured, the water-based epoxy film does not re-emulsify when exposed to moisture. The formulation also inhibits the growth of mould and biological organisms. When used as a vapour barrier system, the dried film must reach a minimum thickness of 0.33mm (330 microns) to achieve its rated 0.12g/24hrs/m²mmHg permeance rating and resist up to 250kPa of hydrostatic pressure.

Numbers that matter

• 0.33mm dry film thickness: The minimum dry film thickness required to block negative vapour pressure.
• 250kPa hydrostatic pressure: Withstands up to a 25-metre head of water when applied at the specified film thickness.
• 4 to 24 hours recoat window: The critical window at 25°C and 50% relative humidity for overcoating. If this window is missed, a fresh coat of Everflex VBS must be applied before applying membranes or paints.
• 1:1 mix ratio: Simple, equal-part mixing by volume or weight of Part A and Part B to prevent curing failure.
• <5g/L VOC: Meets "Green Star" environmental criteria for indoor air quality.

Where to use it

Everflex VBS is suitable for internal and external applications on the following structurally sound substrates:

• Concrete (cured for at least 14 days) and pre-cast concrete (with release agents removed)
• 3:1 sand cement and engineered screeds
• Masonry and cement render (cured for at least 4 days)
• Cement sheeting, underlay, external weatherboard, blue board, Scyon, and AAC systems
• Wet area plasterboard and Villaboard
• Timber flooring, including structural plywood Type A (PAA JAS-ANZ)
• Brickwork and Hebel aggregate blocks

Compatible systems

This primer is formulated for subsequent application of:

• Everflex WPUV, HVUV, WPM Fast cure, and Aqua-Ban membranes
• Polyurethane membranes and 2-part cementitious membranes
• Parquetry adhesives
• Urethane floor coatings

Application and film thickness

Substrates must be clean, stable, free of surface water, and free of form release agents or curing compounds. Mix Part A and Part B in a 1:1 ratio with an electric mixer. Pot life is 2 hours at 25°C, reducing to 1 hour at 35°C.

• As a standard primer: Apply at a rate of 4 to 6 m² per litre by brush or roller. For highly porous surfaces or 14-day-old concrete, apply a secondary coat at the same rate 2 hours after the first is touch-dry.
• As a vapour barrier system: Dilute the mixed batch with 10% water and apply as a wash coat. Apply the first undiluted coat at 5 m² per litre. Fill cracks and voids with VBS repair paste (mixed VBS combined with 1 part Portland cement and 1 part kiln-dried sand) while the first coat is wet. Apply at least 2 additional undiluted coats (waiting 2 hours after touch-dry and within 24 hours) until a minimum 0.33mm dry film thickness is achieved. Do not dilute subsequent coats.
• As an isolation barrier: Apply multiple coats until the area achieves a completely uniform colour.

Limitations

• Do not apply if temperatures are below 10°C or above 35°C during application or cure.
• Do not apply to metallic surfaces.
• Do not apply to wet surfaces with standing or running water, or if rain is imminent.
• Not suitable as an exposed final coating; has limited UV resistance and must be overcoated with a suitable UV-stable topcoat.
• Once fully cured (5 to 7 days), another coat of Everflex VBS must be applied if a membrane or paint coating is to be installed over it.