Fosroc Proofex PGP(X)
Cold-applied, loose-laid PVC membrane with hot-air-welded seams for basements, tunnels, podiums and below-ground structures.
What is it?
A flexible, loose-laid PVC (polyvinyl chloride) synthetic sheet waterproofing membrane from Fosroc, with hot-air-welded seams, designed to form a continuous watertight envelope around buried and roof structures.
Where is it used?
Basement and retaining-wall waterproofing, cut-and-cover and underground tunnels, podium decks, green roofs and covered roofs on building and civil-engineering projects across Delhi NCR and Pan-India.
Why use it?
It is cold-applied (no torch or flame), resists puncture and root penetration, stays flexible at very low temperatures, and welds into a fully homogeneous, watertight joint rather than relying on adhesives at overlaps.
How is it applied?
Rolls are loose-laid over a prepared substrate, overlapped a minimum of 50 mm, and the seams are fused by hand or automatic hot-air welding; detailing at penetrations uses Proofex PGP Flanges for future re-injectable compartment systems.
About Fosroc Proofex PGP(X)
Fosroc Proofex PGP(X) is a loose-laid PVC (polyvinyl chloride) waterproofing membrane and a member of the wider Proofex PGP family (the range was formerly marketed as Proofex Alkorplan). It is engineered to deliver a continuous, fully welded waterproof barrier for building and civil-engineering structures, and is particularly suited to below-ground construction where reliable, long-term watertightness is non-negotiable.
Unlike liquid-applied or torch-on bituminous systems, Proofex PGP(X) is a factory-made flexible sheet that arrives on site ready to deploy. It is laid out cold over the prepared surface and individual sheets are joined by fusing the PVC with hot air, so the overlaps become a single homogeneous skin rather than a glued lap that can creep or peel over time. The membrane carries a two-tone construction — a light-grey upper face over a black underside — so that any cut, puncture or weld defect during installation is immediately visible against the contrasting layer, which makes site quality control straightforward.
For Indian projects this matters because basements, metro and road tunnels, STP/WTP tanks and landscaped podiums routinely sit in high water tables and aggressive ground conditions. The (X) designation denotes the loose-laid PVC grade within the Proofex PGP system; both Proofex PGP and Proofex PGP(X) are listed in Fosroc India’s product range as loose-laid PVC waterproofing membranes. Loose-laid installation tolerates minor substrate movement and shrinkage cracking without stressing the membrane, and — when configured with Proofex PGP Flanges into compartmented zones — allows any future leak to be isolated and re-grouted by resin injection without exposing the whole structure. This combination of cold safe application, welded watertightness and re-injectable detailing is why consultants specify PVC sheet systems for critical, hard-to-access waterproofing.
The technical insight
The performance of Proofex PGP(X) comes from plasticised PVC sheet technology rather than a chemical reaction on site. The base membrane is a flexible PVC sheet available in thicknesses of 1.5, 2.0, 2.2, 2.5 and 3.0 mm (thickness tolerance −5/+10% per EN 1849-2), so the designer can match gauge to hydrostatic head and puncture risk. Tested to ASTM D412 / EN 12311-2 it develops about 16.5 N/mm² tensile strength longitudinally and 15 N/mm² transversally, with roughly 300% elongation at break in both directions — meaning it can bridge minor settlement and shrinkage cracks without splitting. Puncture resistance reaches a maximum load near 1200 N (ASTM E154), and the sheet shows no penetration under water-impermeability testing at 5 bar pressure (BS EN 12390-8), which corresponds to a substantial water head. The system is also root- and micro-organism-resistant and stays flexible (cold bending per EN 495-5 to below −30°C), making it suitable for green-roof and cold-climate work. The decisive engineering feature, though, is the joint: overlaps are hot-air welded to a minimum 50 mm weld so the seam itself is PVC-to-PVC fused. Welded lap-joint strength is reported in the order of 1000 N/5cm. Because the membrane is loose-laid (not adhered across its full area in the standard grade), it is not dependent on substrate bond and accommodates differential movement — the membrane stays intact even if the substrate behind it cracks.
Where it is used
- Tanking of RCC basements, lift pits and retaining walls below the water table
- Cut-and-cover tunnels and other underground civil-engineering works
- Podium decks and planter areas over occupied or parking space
- Green roofs and landscaped terraces requiring root resistance
- Covered and concealed roof waterproofing
- Water-retaining and water-excluding tank structures (with appropriate detailing)
- Compartmented waterproofing zones with Proofex PGP Flanges for future re-injection
Key advantages
- Cold-applied — no naked flame or torch, improving site safety and allowing use near combustibles
- Hot-air-welded seams create a homogeneous, fully watertight joint instead of an adhesive lap
- Two-tone grey-over-black sheet makes punctures and weld faults easy to spot for QC
- High flexibility retained at very low temperatures (cold bending below −30°C)
- Good puncture resistance (around 1200 N) for rough substrates and backfilling
- Resistant to root penetration and micro-organisms — suited to green roofs and buried use
- Loose-laid system tolerates substrate cracking and minor movement
- Compatible with Proofex PGP Flanges to build re-injectable compartment systems
- Non-flammable PVC sheet
- Fast roll-out application over large areas
Limitations & considerations
- Not intended for permanent exposure — heat, direct sunlight or UV can cause colour change and degradation, so it must be covered/protected
- Requires skilled, Fosroc-approved applicators and hot-air welding equipment; weld quality is the critical control point
- Substrate must be free of cavities, projecting nibs and running/standing water before laying
- PVC membranes can be incompatible with bitumen, tar and certain solvents/oils — separation layers may be needed
- Rolls must be stored horizontally, no more than one pallet high, in a cool dry place away from heat
- As a loose-laid sheet it needs protection (e.g. protection board/screed) before backfilling or trafficking
- Mechanical damage during follow-on trades must be guarded against until the membrane is covered
Selection & best practice
Specify the membrane gauge to suit the hydrostatic head and puncture risk — typically 1.5–2.0 mm for general below-ground tanking and 2.2–3.0 mm where backfill is aggressive or heads are high. Prepare the substrate so it is sound, smooth and free of cavities, projecting nibs and standing water; lay a geotextile or protection fleece where the concrete is rough. Loose-lay the rolls, overlap a minimum of 50 mm and hot-air weld every seam — hand-weld at details and use automatic welding machines on long runs — then probe-test the welds. Design the area into compartments using Proofex PGP Flanges so any future leak can be isolated and resin-injected without lifting the whole membrane. Never leave the membrane permanently exposed: install Proofex Protection Board or a protective screed before backfilling, laying ballast or trafficking. Always engage Fosroc-approved applicators and follow the project method statement and current Fosroc TDS.
Specifications
| Product type | Loose-laid PVC (polyvinyl chloride) waterproofing membrane |
| Membrane thickness | 1.5, 2.0, 2.2, 2.5 & 3.0 mm (tolerance −5/+10%, EN 1849-2) |
| Colour | Upper layer light grey / lower layer black (signal layer for damage detection) |
| Tensile strength (ASTM D412 / EN 12311-2) | Longitudinal 16.5 N/mm²; Transversal 15 N/mm² |
| Elongation at break | approx. 300% longitudinal and transversal |
| Puncture resistance (ASTM E154) | Maximum load approx. 1200 N |
| Water impermeability (BS EN 12390-8) | No penetration at 5 bar pressure |
| Tear resistance (ASTM D624) | approx. 50 N/mm (longitudinal & transversal) |
| Welded lap-joint strength (UEATc) | approx. 1000 N/5 cm |
| Cold bending (EN 495-5) | No cracking below −30°C |
| Root / micro-organism resistance | No penetration (resistant) |
| Minimum weld overlap | 50 mm, hot-air welded (hand or automatic) |
| Roll size (1.5 / 2.0 / 2.2 mm) | 25 m long x 2.10 m wide |
| Roll size (2.5 / 3.0 mm) | 20 m long x 2.10 m wide |
| Fire | Non-flammable |
| Ancillary | Proofex PGP Flange 180 mm (re-injection connector, boxes of 10) |
Industry use cases
Metro & Infrastructure
Cut-and-cover tunnel sections and underground stations where a cold-applied, fully welded membrane avoids hot works in confined spaces and provides a re-injectable compartment system.
Commercial & Residential Basements
Tanking of deep basements, lift pits and raft slabs in high-water-table city sites across Delhi NCR, with welded seams giving reliable watertightness under hydrostatic head.
Landscaped Podiums & Green Roofs
Root-resistant membrane under planters, lawns and podium gardens over parking or habitable space, protected by a board or screed before soil and paving are placed.
Water & Wastewater
Below-ground tank and chamber waterproofing on STP/WTP and utility structures where flexibility over construction joints and crack-bridging are required.
Civil & Industrial Structures
Buried structures, plant rooms and service tunnels needing a durable, puncture-resistant barrier that tolerates backfill and minor substrate movement.
Frequently asked questions
What exactly is Fosroc Proofex PGP(X)?
How is it different from standard Proofex PGP?
What thicknesses and roll sizes are available?
How are the joints made watertight?
Can leaks be repaired after the structure is built?
Can Proofex PGP(X) be left exposed to sunlight?
Is it available in India and who can apply it?
How we position Fosroc Proofex PGP(X)
Proofex PGP(X) sits at the premium, engineered end of Fosroc’s waterproofing portfolio: a loose-laid PVC sheet system for structures where failure is costly and access for repair is limited — deep basements, tunnels and podiums. Within the Fosroc range it is most naturally specified alongside Proofex PGP and Proofex PGP GTX (the fully-bonded geotextile-backed grade), Proofex PGP Flange (for re-injectable compartments), Proofex Protection Board (to shield the membrane before backfill), and Fosroc’s HDPE pre-applied systems such as Proofex Engage. For positive-side liquid or self-adhesive solutions, contractors often pair or compare it with Fosroc Brushbond/Nitoproof coatings depending on the substrate and exposure. Against the wider Indian market, credible PVC and TPO single-ply alternatives include Sika Sikaplan, while loose-laid/pre-applied HDPE competitors include systems from MBS (Multibase/CICO) and STP; for cementitious and liquid-membrane basements, Dr. Fixit (Pidilite) and Sika are common reference brands. The key differentiator for Proofex PGP(X) is its combination of cold welded PVC sheet, strong crack-bridging flexibility, root resistance and the option to build re-injectable compartment systems — a specification-grade solution rather than a general-purpose coating. Space Arc Engineering, as an authorised Fosroc distributor and applicator serving Delhi NCR and Pan-India, can advise on the correct grade, thickness and detailing, and arrange Fosroc-approved installation.
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