About Fosroc Proofex Self Adhesive PR 30

Fosroc Proofex Self Adhesive PR 30 sits at the top of Fosroc’s cold-applied self-adhesive PR range, which steps up in thickness from the 1.5mm PR 15 through the 2mm PR 20 to this 3mm grade. The extra body matters where a membrane has to survive a rough concrete face, back-filling, reinforcement traffic and years of hydrostatic load. It is built from an SBS-modified bitumen adhesive compound, internally reinforced with a polyester carrier and faced with a cross-laminated polyethylene film. The bitumen side arrives protected by a siliconised release paper that the applicator strips off on site, so no melting, boiling or torching is involved at any stage.

For engineers working on Delhi NCR basements or pan-India infrastructure, the appeal is predictability. A sheet membrane cannot be applied too thin or too thick the way a brushed coating can, which removes a common source of below-grade waterproofing failures. Because PR 30 bonds cold, it suits deep excavations, plant rooms and tunnels where an LPG torch would be a genuine fire and ventilation hazard. Space Arc Engineering supplies PR 30 as an authorised Fosroc distributor and applicator, and can pair it with the correct Proofex primer, corner pieces and protection board so the full tanking system is specified from one source.

The technical insight

The membrane works because two materials do two different jobs. The SBS (styrene-butadiene-styrene) modification turns ordinary bitumen into a rubber-like elastomer: it stays flexible in the cold, recovers after being stretched, and re-seals around minor punctures instead of cracking. That elastomeric bitumen is the waterproofing barrier and the adhesive in one. The embedded polyester reinforcement carries the tensile load, so the sheet resists tearing when a raft settles, a wall shrinks or the membrane is dragged over an arris during laying. The cross-laminated polyethylene film on the outer face then shields the bitumen from UV before burial and from mechanical damage during back-filling. Crucially, the bond is achieved by the tack coat primer, not by heat, so adhesion depends on the substrate being genuinely dry and dust-free rather than on an operator’s torching skill. Get the priming right and you get a continuous, fully-adhered barrier with no water tracking path behind it.

Where it is used

• Tanking basement raft slabs and retaining walls in positive-side (external) configuration
• Waterproofing water-retaining structures such as tanks and sumps
• External waterproofing of cut-and-cover tunnels and underpasses
• Podium decks and buried slabs above occupied space
• Foundation and pile-cap protection against aggressive ground water and soluble salts
• Below-grade utility structures, subways and service ducts
• Protecting concrete substrates on congested urban sites where open flame is prohibited
• Vertical and horizontal surfaces on concrete, masonry and metal decks after priming

Key advantages

• Cold-applied and self-adhesive, so no torch, no LPG cylinders and no open-flame permit on site
• Uniform factory-controlled 3mm thickness removes the thin-spot risk of brushed or sprayed coatings
• SBS modification keeps the sheet flexible in the cold and lets it bridge fine shrinkage movement
• Polyester reinforcement gives high tear and puncture resistance during back-filling
• Cross-laminated polyethylene facing protects against UV before cover and mechanical damage after
• Bonds to primed concrete, masonry and metal decks, both horizontal and vertical
• Fast to lay with simple peel-and-roll installation, speeding up the below-grade critical path
• Backed by Fosroc’s Proofex accessory system – tack coat, corner pieces and protection board

Limitations & considerations

• Adhesion depends on a genuinely dry, dust-free substrate; damp or green concrete will not bond
• Working window is roughly 5C to 50C, and below about 15C the membrane back may need gentle warming
• Substrate must be primed with Proofex Tack Coat and re-primed if left exposed beyond 24 hours
• Laid membrane must be protected quickly with protection board or a sand/cement screed before back-filling
• It is a positive-side external system, not a substitute for internal negative-side repair on an existing wet basement
• Monsoon and standing-water conditions demand sequencing and protection to keep the surface dry during application

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Proofex Self Adhesive PR 30

Within the Fosroc self-adhesive family, choose PR 30 (3mm) over PR 20 (2mm) or PR 15 (1.5mm) when the membrane must take back-fill abuse and higher head; the thinner grades suit lighter roof-slab and damp-proofing duties. Where site rules permit heat application and you want higher softening-point performance, Fosroc Proofex Torchseal is the torch-applied counterpart. For brush- or spray-applied alternatives on terraces and exposed slabs, Fosroc Nitoproof 600 covers liquid bitumen-polymer membrane duty. Space Arc also stocks comparable below-grade systems from other brands – Dr. Fixit, Sika and STP – so specifiers can match the membrane to the exact substrate, programme and budget.

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