When preparing concrete slabs or substrates for critical finishes like waterproofing membranes, flooring, or coatings, moisture and bond are the two biggest variables. Everflex VBS brings certainty to both. This two-part, water-based epoxy primes damp and common building materials while also acting as a robust negative hydrostatic vapour barrier. It’s the reliable first step, ensuring your topcoats adhere correctly and moisture stays where it belongs.

Why this product exists

Everflex VBS was engineered to solve a dual problem on construction sites: the need for a high-performance primer that performs on damp or 'green' substrates, and a reliable barrier against negative hydrostatic pressure. Its water-based, low VOC formulation means you meet Green Star environmental criteria without compromising on performance. It seals the substrate, inhibits mould, and ensures subsequent layers like membranes or self-levelling compounds bond securely without risk of re-emulsification once cured.

The numbers that matter

  • Negative hydrostatic pressure up to 25m (250 kPa): This product effectively resists significant water pressure from below the slab, preventing moisture ingress that can lead to delamination of subsequent finishes. Achieve this at a minimum dry film thickness of 300 microns.
  • VOC content below 5g/L: Meeting Green Star criteria, Everflex VBS contributes to healthier indoor air quality without the strong odours often associated with epoxy primers.
  • 2-hour pot life at 25°C: This working time ensures you have ample opportunity to mix and apply the product across larger areas without rush, reducing waste. Recoat within 4 to 24 hours to maintain optimal adhesion between coats.
  • Full cure in 5-7 days: While it allows overcoating quickly, the full cure time means the epoxy network develops its maximum strength and impermeability, delivering long-term resistance to water and chemical attack.

What it's like to use

Preparation is key: ensure all surfaces are clean, dry (no surface water), structurally sound, and free from contaminants. Concrete requires 14 days cure, and sand-cement screeds 4 days. Mix Part A and Part B in equal volumes until a uniform colour appears. If thinning is needed for highly porous substrates, do it with water at the initial mixing stage. Apply with a brush or roller, ensuring even coverage. For vapour barrier applications, apply a diluted wash coat first, then minimum two undiluted coats to achieve the required film thickness. Clean tools and spills with water while the product is still wet.

Where this product excels

  • Roofing — concrete roofs, membrane-covered tiled: Use as an all-areas primer, crack primer, or hydrostatic barrier on concrete roofs. Its ability to prime damp substrates is critical where residual moisture might otherwise compromise membrane adhesion.
  • Balconies, podiums, door/window reveals, flashings: Essential as a concrete primer before waterproofing membranes, especially around critical detailing like waste outlets where it supports butanol-based joint tape systems. It ensures a stable, moisture-resistant base for lasting performance.
  • Crack & joint treatment — detailing and repair: When preparing cracks or joints for a polyurethane sealant, Everflex VBS primes the area, improving adhesion and preventing moisture migration from below. You can also combine it with Portland cement and kiln-dried sand to create a repair paste.
  • Plant rooms, lift motor rooms, commercial internal: Crucial for its vapour barrier capabilities, preventing rising damp from impacting sensitive equipment or floor coatings. It forms a durable, low-permeability layer for demanding commercial environments.

How it fits in a real system

Everflex VBS consistently serves as the foundational step in demanding build-ups. It is the first product applied during substrate preparation, particularly for roofing, balconies, and internal plant rooms, often followed by waterproofing membranes or self-levelling compounds. For waste outlets and penetrations, it primes the area to ensure the subsequent sealing layers, such as a polyurethane joint sealant, achieve optimal bond and moisture resistance.

Choose this when

  • When priming damp or green concrete: Provides excellent adhesion and a reliable moisture barrier even when concrete has cured for only 14 days.
  • For negative hydrostatic pressure: Use when water pressure comes from below the slab, protecting your finishes from lift-off and degradation.
  • Preparing for waterproofing membranes or floor coatings: It creates a tough, durable base layer compatible with a wide range of topcoats and flooring systems.
  • Green Star rated projects: Its low VOC content supports environmental and health standards.

Don't use this when

  • Not for: Application outside its temperature range of 10°C to 35°C; ensure conditions are suitable for cure.
  • Not for: Direct application to metallic surfaces, as it is formulated for porous and common building substrates.
  • Not for: Long-term UV exposure without overcoating; its limited UV resistance means it must be protected by a suitable topcoat or membrane.
  • Not for: Surfaces with standing or flowing water, or if rain is imminent; ensure the substrate is free from surface water for proper adhesion.

Everflex VBS features low VOC content, supporting Green Star environmental criteria for sustainable building practices. Its water-based, non-toxic formulation enhances site safety and reduces environmental impact.