Gripset BRW PFN

Gripset BRW PFN is a self-adhesive, fibre-faced butyl-rubber sheet membrane for internal and external floor waterproofing. The fabric-laminated face accepts compatible toppings and tiled finishes, while the butyl backing provides immediate adhesion and strong resistance to movement, vibration and cracking.

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How it works

BRW PFN functions as a hybrid sheet-and-liquid system. The self-adhesive butyl backing bonds to prepared substrates, while the top fabric face provides a mechanical key for cement-based toppings and tile adhesives. For critical junctions and joins, the system integrates with Gripset liquid membranes to create a continuous waterproof seal. It also acts as an anti-fracture system, absorbing vibration and flexing over cracked concrete and floor substrates to prevent cracks from reflecting through to the finished tile layer. Because it is cold-applied, it seals instantly upon contact without the safety risks of torching, heat welding, or solvent-based adhesives.

Numbers that matter

• Class II membrane: Accommodates floor movement and vibration in internal and external wet areas in compliance with AS 4858 and AS 4654.1.
• >60% elongation (AS1145.3): Extends to absorb substrate movement without tearing or rupturing.
• >2MPa tensile strength (AS 4654.1 Appendix A): Provides structural toughness under screeds, toppings, and heavy tiles.
• 0.1g/24h/m² water vapour transmission (ASTM E96): Restricts vapour transmission, preventing moisture buildup under tiled floor assemblies.
• -30°C to 80°C service temperature: Resists extreme temperature cycling on exposed external balconies and decks without cracking or degrading.

Where to use it

Suitable for commercial, industrial, and residential floor applications over these substrates:

• Concrete and screeds
• Compressed fibre cement sheeting
• Timber sheeting and structural plywood
• Most metals, including galvanised iron, zincalume, stainless steel, copper, and aluminium
• Glazed surfaces, marble, granite, and ceramics
• Soft and rigid plastics, PVC, and DPC films
• Existing epoxy coatings

Limitations

• Suitable for floor and horizontal surfaces only. Do not use over vertical surfaces to support tiles or other finishes.
• Do not apply when surface or ambient temperatures are below 5°C or above 30°C.
• Not to be used as an exposed membrane finish; must be finished over with a topping, screed, or tiles.
• Not to be used as a trafficable surface.
• Do not install directly over expansion joints.
• Not compatible with solvent-based finishes applied over the membrane.

Preparation and priming

Concrete must be cured for at least 28 days; cement render and sand-cement screeds must cure for at least 7 days. Ensure all surfaces are clean, dry, and free of laitance, curing compounds, and contaminants. Mechanically remove unsound layers by grinding or abrasive blasting.

While priming is generally not required on clean, non-porous, non-mineral surfaces like metals, plastics, and glazed surfaces, mineral substrates must be primed prior to sheet application:

• Porous/absorbent surfaces: Prime with Gripset GP Primer at a minimum coverage rate of 1 L per 8–10m².
• Non-porous/non-absorbent surfaces: Prime with Gripset OP Primer at a minimum coverage rate of 1 L per 12m².
• Green/damp surfaces and external floors: Apply 1 to 2 coats of Gripset E60 at a minimum coverage rate of 1 L per 3m² per coat.

Installation and detailing

Unroll the sheet, cut to length, and remove 100mm to 200mm of the release paper to tack the sheet in place. Slowly peel back the remaining release paper while unrolling, smoothing out air bubbles with a flat trowel, float, or heavy roller. On sloped surfaces, always start laying from the lowest point near the drain and work upwards to prevent counter-gradient overlaps.

• Overlaps: All vertical and horizontal sheet joins must have a minimum 50mm overlap, using the patterned squares on the fabric face as a guide. Press overlaps firmly with a hand-held vinyl roller. All joins must be coated with a 100mm-wide liberal coat of a suitable Gripset liquid membrane applied centrally across the overlap.
• Pipes and penetrations: Cut a "+" cross in the sheet to slide over the pipe, trim loose membrane around the upturn, and seal the penetration with a liberal coat of a Gripset liquid under-tile membrane. Alternatively, use Elastoproof Collars.
• Floor wastes: Adhere the sheet directly over the waste flange, then cut an aperture to reveal the waste.
• Edge terminations: Where the sheet terminates horizontally without a wall upturn (such as balcony edges), apply BRW PF Tape or RLA Waterproof Bandage centrally over the edge, turn it down over the fascia, and seal with a Gripset liquid under-tile membrane.
• Perimeter bond breakers: Detail wall/floor junctions using Elastoproof B50 Joint Band embedded in a coat of Gripset liquid membrane, or apply self-adhesive BRW PF Tape centrally over the joint, rolling it firmly before encapsulating it in the liquid membrane.

Tiling and toppings

When tiling directly over BRW PFN, always use polymer-modified cement-based adhesives such as Gripset C-LITE, C-MASTIC, or C-RUBBER. If applying a sand-cement screed, render, or concrete topping over the installed membrane, incorporate Gripset 11Y as a proprietary bonding agent and water-resistant additive into the mix, or use GRIPSET C-BED engineered screed.