About Fosroc Proofex Self Adhesive Geotext

Fosroc Proofex Self Adhesive Geotext is a pre-formed, cold-applied sheet waterproofing membrane built specifically for below-ground (sub-structure) tanking. Each sheet is a 2 mm thick laminate: an internally reinforced polymer-modified bitumen compound forms the self-adhesive core, while the outer face carries a 250 GSM (250 micron) laminated geo-fabric film. The underside of the bitumen layer is protected by a siliconised release paper that is peeled away just before the membrane is rolled onto a tack-coat-primed substrate. The result is a fully bonded, continuous waterproof barrier rather than a loose-laid sheet — a distinction that matters underground, because a bonded membrane prevents lateral water tracking between membrane and concrete if the barrier is ever locally breached.

The product sits in Fosroc’s well-established Proofex family of pre-formed membranes, which Indian consultants and contractors have specified for decades. Its defining feature is the geotextile (geotext) facing. Unlike a plain HDPE-faced self-adhesive sheet, the fibrous geo-fabric top surface provides mechanical robustness and a key for subsequent screeds or protection layers, and it is tough enough that reinforcement can, in appropriate details, be placed directly over it. Because the membrane is cold-applied and self-adhesive, there is no torch, no gas cylinder and no open-flame risk on site — a genuine advantage in occupied or congested urban sites in Delhi NCR where hot-works permits and fire safety are a constant concern.

For a distributor-applicator like Space Arc Engineering, Proofex Self Adhesive Geotext fills the gap between liquid-applied coatings (fast on complex geometry but operator-dependent on thickness) and torch-applied APP/SBS felts (proven but flame-dependent). It is most at home on large, relatively flat or simply detailed below-ground surfaces — basement rafts, blinding-level horizontal tanking, retaining-wall faces and podium slabs — where a factory-controlled 2 mm thickness and a self-adhesive bond give predictable, repeatable performance. It is supplied with its companion primer, Proofex Tack Coat, and a family of accessories (corner pieces, protection board) that complete the system.

The technical insight

The core is a polymer-modified bitumen (PMB) adhesive compound, internally reinforced and laminated to a 250 GSM geo-fabric film — not a plain bitumen sheet. Two numbers explain its behaviour. First, the bitumen compound itself shows elongation in excess of 2000% to ASTM D 146, which is what lets the fully cured membrane accommodate substrate movement and minor cracking without rupturing; the composite membrane’s measured elongation is around 40-41% longitudinal/transverse to ASTM D 638 because the geotextile reinforcement governs the laminate. Second, the membrane is rated against 60 m head of water (ASTM D 5385 hydrostatic resistance) and passes DIN 52123 water-pressure testing with no leakage — comfortably covering the static heads seen in most Indian basements. The 115°C softening point (ASTM D 36) and cold flexibility with no cracking at 0°C to -5°C (ASTM D 836) bracket its service temperature window. The decisive site variable is bond: the self-adhesive grab depends entirely on a correctly applied, fully tack-free Proofex Tack Coat primer and a clean, dry, frost-free, laitance-free concrete substrate. Below 15°C the membrane back may need slight warming and material should be conditioned above 20°C to develop immediate adhesion. Get the priming and the 75 mm/150 mm laps right and the system performs to its hydrostatic rating; skimp on either and the bond — not the sheet — becomes the weak point.

Where it is used

• Continuously bonded tanking to basement raft slabs and blinding-level horizontal surfaces
• Vertical waterproofing of retaining walls and basement perimeter walls (laid low-to-high)
• Below-ground waterproofing of water-retaining and civil-engineering substructures
• Podium decks and buried slabs requiring a fully bonded barrier
• Underground car parks, tunnels and similar sub-structure envelopes
• Pre-applied / bonded tanking where rebar or reinforcement is placed over the geotextile face

Key advantages

• Cold-applied and self-adhesive — no torch, no flame hazard, faster and safer on congested or occupied sites
• Factory-controlled 2 mm thickness gives consistent, repeatable barrier performance independent of applicator skill
• Fully bonded to the substrate, preventing lateral water tracking if the membrane is locally breached
• 250 GSM geotextile face provides puncture resistance, mechanical robustness and a key for screeds; rebar can be placed directly in suitable details
• High hydrostatic resistance — rated to 60 m water head (ASTM D 5385), no leakage under DIN 52123
• High elongation in the bitumen compound (>2000% to ASTM D 146) accommodates thermal movement and minor substrate cracking
• Environment-friendly with no significant health hazards in normal use; 12-month shelf life

Limitations & considerations

• Performance is entirely dependent on correct priming with Proofex Tack Coat and a dry, frost-free, laitance-free substrate — poor surface prep causes bond failure
• Application temperature limited to 5°C-50°C; below 15°C the membrane back may need warming and the roll must be conditioned above 20°C
• Self-adhesive sheets are best suited to flat or simply detailed surfaces — complex geometry, many penetrations and tight upstands are slower and need corner pieces and detailing strips
• Bituminous sheet, so it is flammable in storage and must be kept away from ignition sources (flash point >65°C)
• Rolls must be stored horizontally, no more than one pallet high, in a cool dry place; 12-month shelf life
• Not a self-healing or pre-applied/anchored system — it does not chemically bond to subsequently poured concrete the way some HDPE pre-applied membranes (e.g. Proofex Engage) do

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Proofex Self Adhesive Geotext

Within Fosroc’s own range, Proofex Self Adhesive Geotext is the cold, self-adhesive, fully-bonded sheet option that sits between liquid-applied systems (Fosroc Brushbond / Proofex LM) and the pre-applied, mechanically-keyed HDPE membrane Proofex Engage — the latter being the better choice where you need a membrane cast monolithically against fresh concrete with no water tracking. For protection and detailing it pairs with Proofex Tack Coat, Proofex Corner Pieces and Proofex Protection Board, and for simpler tanking it overlaps with Proofex 3000 self-adhesive membranes. Against the wider market, credible alternatives an Indian consultant might compare include Sika’s self-adhesive and pre-applied membranes (e.g. SikaProof / Sika BlackSeal), STP Limited’s bituminous self-adhesive tapes and membranes, MBCC/MBS (formerly BASF) waterproofing systems, and the Dr. Fixit range from Pidilite for self-adhesive bitumen membranes. As authorised Fosroc distributors and applicators serving Delhi NCR and Pan-India, Space Arc Engineering positions Proofex Self Adhesive Geotext for clients who specifically want a factory-controlled, flame-free, geotextile-protected bonded membrane backed by Fosroc’s system warranty and on-site technical support, rather than the lowest-cost generic SBS felt.

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