Everflex HVUV Elastomeric Waterproof Membrane

Everflex HVUV is a high-viscosity, UV-stable Class III elastomeric waterproof membrane for exposed roofs, balconies, decks and demanding wet-area applications. Its micro-fibre-reinforced formulation is designed to build a robust seamless film while retaining high flexibility.

Compare waterproofing systems: Browse the full waterproofing membrane range to compare liquid, sheet, cementitious and trafficable systems. For this format, also compare our liquid waterproofing membranes. Always match the membrane to substrate, exposure, movement, immersion, traffic and finish requirements.

Best fit in the Everflex range

Choose HVUV when the project needs the Everflex UV membrane system with a higher-viscosity, high-build application profile. The current WPUV/HVUV technical data sheet publishes the same Class III classification, minimum film thickness, cure window and substrate requirements for both products; WPUV remains the standard UV-stable option where the higher-viscosity profile is not required. For under-tile work that will be covered, use Aqua-Ban or WPM instead.

How it works

Everflex HVUV uses a water-based acrylic-styrene and polyurethane co-polymer system reinforced with micro-fibres to achieve Class III high permanent flexibility. It forms a fully bonded, UV-stable membrane but does not replace proper joint detailing: gaps and active joints still require the specified sealant, bond breaker or joint-band system. Once cured, the membrane is suitable for UV exposure and maintenance foot traffic within the limits of the current technical data sheet.

Numbers that matter

• Class III Elongation: High permanent flexibility designed to accommodate substrate movement without rupture.
• 1.0mm Minimum DFT (Internal): The minimum dry film thickness required across internal applications to meet waterproofing standards, typically requiring 1.5 litres per square metre.
• 1.3mm Minimum DFT (External): The minimum dry film thickness required to ensure long-term UV and weathering protection on exposed external areas.
• 2.2g/m²/24h Permeability: Low moisture vapour transmission rate to prevent passage of water through the cured film.
• 48 Hours Cure Time: Required drying time at 25°C and 50% relative humidity before tiling or finishing.

Where to use it

Suitable for installation over the following prepared substrates:

• Concrete cured for a minimum of 28 days.
• 3:1 sand cement screeds, C-Bed engineered screeds, and masonry or render cured for at least 4 days.
• Cement sheeting, underlay, external weatherboard, and blue board.
• Pre-cast concrete with all release agents fully removed or dissipated.
• Wet area plasterboard and Villaboard.
• Timber flooring including structural plywood Type A (PAA JAS-ANZ).
• Brickwork and Hebel aggregate blocks.

Common applications include exposed roofs, pedestal system sub-floors, shower recesses, laundries, toilets, kitchens, patios, terraces, decks, balconies, and under-tile installations.

Limitations

• Do not apply if the ambient or substrate temperature is below 10°C or above 35°C.
• Do not apply on damp, wet, or contaminated substrates, or if rain is imminent.
• Not suitable for structures subject to negative hydrostatic pressure or rising damp.
• Not suitable for traffic areas subjected to regular foot traffic heavier than standard maintenance access.
• Light Grey has a Solar Reflectance Index (SRI) of approximately 0.32; adding up to 75ml of black Glycol tint will alter the colour and reduce this SRI rating.

Installation and system components

All surfaces must be clean, dry, and free from protrusions, release agents, curing compounds, or dust. Non-structural cracks and holes must be filled prior to application. Apply a fillet of Adheseal Hi-Flex MS sealant to all internal corners and sheet joints. Floor wastes and puddle flanges must be rebated into the floor and sealed with Hi-Flex MS sealant.

For internal priming, use Everflex WBP. For external balconies and roof decks, prime with Everflex VBS. Apply the membrane within 2 to 24 hours of the primer becoming touch-dry.

Mix Everflex HVUV thoroughly before application. Apply the first coat with a brush or roller at approximately 0.75mm wet film thickness (WFT). Once dry, apply the second coat at a right angle to the first at 0.75mm WFT. Verify the wet film thickness during application using a WFT gauge to ensure the target dry film thickness (1.0mm internal / 1.3mm external) is achieved. For additional UV and mechanical protection, the membrane can be coated with LS slip-resistant UV protective coating.