About STP ShaliPVC

{“name”:”ShaliPVC”,”slug”:”stp-shalipvc”,”brand”:”STP”,”realProduct”:”yes”,”officialSource”:”https://stpltd.com/wp-content/uploads/2022/01/ShaliPVC.pdf”,”category”:”waterproofing”,”metaTitle”:”ShaliPVC | PVC Waterproofing Membrane | Space Arc”,”metaDescription”:”STP ShaliPVC is a 2mm non-reinforced PVC geomembrane for tunnel, basement and protected-roof waterproofing, hot-air welded for a fully sealed liner.”,”heroSubtitle”:”A 2 mm PVC geomembrane liner for tunnels, basements and protected roofs, loose-laid and hot-air welded into a continuous barrier rated to hold back water at 6 bar for 72 hours.”,”glance”:{“whatIsIt”:”A non-reinforced, opaque PVC (polyvinyl chloride) geomembrane with a twin-colour signal layer, supplied in 2 mm thick rolls and joined on site into one continuous sheet by hot-air welding, not adhesive lapping.”,”whereUsed”:”Below-grade and covered structures that need a fully welded, high-integrity barrier: metro and road tunnels, basement raft slabs and retaining walls, underground tanks, and protected (inverted) roof build-ups where the membrane sits under insulation and screed, shielded from UV and foot traffic.”,”whyUse”:”Loose-laid, welded PVC doesn’t depend on perfect bond to the substrate the way a self-adhesive or bituminous membrane does. Every seam is fused and can be individually tested, which matters on uneven tunnel shotcrete, raft slabs with rebar projections, or any surface a contractor can’t guarantee will be dry and clean on the day of laying.”,”howApplied”:”Laid loose over a ShaliGeo protective geotextile (never directly on bare concrete), with 75 mm overlaps at every joint fused by hot-air welding, terminated at parapets and upstands with a screwed termination strip sealed with ShaliSeal PU, then covered by a second geotextile layer and protection screed before backfill or the next construction stage.”},”about”:”ShaliPVC is STP Limited’s PVC geomembrane liner, built for the specific job of sealing tunnels, basements and protected roofs where a fully welded, testable barrier matters more than a fast-curing bonded coat. STP has been in the waterproofing business since 1935 and markets ShaliPVC alongside its ShaliGeo geotextile and ShaliSeal PU sealant as a matched loose-laid liner system rather than a standalone sheet. Space Arc Engineering supplies and installs it across Delhi NCR and pan-India as an authorised STP distributor and applicator, which matters here more than with most waterproofing products because welding quality, not the membrane itself, decides whether a PVC liner actually holds water.\n\nWhat sets a loose-laid PVC system apart from the self-adhesive and bituminous membranes that dominate basement tanking in India is that it doesn’t ask the substrate to be perfect. The sheet floats over a geotextile cushion and the joints are heat-fused into one continuous skin, so it tolerates the kind of rough shotcrete, rebar stub-ups and minor settlement that would compromise a bonded membrane’s adhesion. That flexibility is also why it’s specified on transit tunnels and large basement rafts rather than smaller residential jobs, where the cost of a trained welding crew is harder to justify against a simpler cementitious or bituminous system. On any project where Space Arc proposes ShaliPVC, the scope is priced to include supply, geotextile protection layers on both faces, welded seam testing and termination detailing, not just the roll itself.”,”technicalInsight”:”The number worth understanding on ShaliPVC’s data sheet is the 6 bar / 72 hr water pressure rating, roughly equivalent to a 60 metre static head, tested well beyond what most basement or tunnel water tables actually generate. The ≥275% elongation figure is the other one that matters in practice: PVC geomembranes need that stretch to absorb the differential movement that happens as concrete cures, settles and creeps around them without splitting at a weak point. Puncture resistance is reported as an indentation class (Static L-2, Dynamic I-2) rather than a raw force figure, which is standard for geomembranes and is exactly why the installation sequence sandwiches the sheet between geotextile layers on both sides — the membrane’s own puncture resistance is only ever the second line of defence, the geotextile cushion is the first. Because ShaliPVC is non-reinforced, it relies entirely on that protection detail; a reinforced, fabric-backed geomembrane trades some of the flexibility for higher intrinsic tear resistance and is the product to ask for if the cover system can’t be guaranteed.”,”applications”:[“Metro, road and utility tunnel lining, cut-and-cover and NATM sections alike”,”Basement raft slab and retaining wall tanking, sandwiched between two geotextile layers”,”Underground water tanks, reservoirs and lift pit tanking below the water table”,”Protected (inverted) roof and podium deck waterproofing under insulation and paver ballast”,”Diaphragm wall and blindside basement wall lining before the internal concrete pour”,”Car park and substructure waterproofing beneath paving in multi-level basements”,”Cable and service tunnels where a fully welded, leak-testable liner is specified”,”Termination and detailing at parapets, upstands and penetrations in combination with ShaliSeal PU”],”advantages”:[“Fully hot-air welded seams fuse into one homogeneous sheet rather than relying on adhesive lap bonding”,”Welds can be needle or vacuum tested during installation, giving a verifiable seal before backfill”,”≥275% elongation absorbs minor substrate movement and settlement without the membrane splitting”,”Verified to hold back water at 6 bar for 72 hours, suited to genuinely high water-table sites”,”Root and oxidation resistant for a long service life once buried and covered”,”Loose-lay application doesn’t demand a perfectly dry, primed substrate the way bonded membranes do”,”Stays flexible down to -20°C with no cracking, useful on cold-store and high-altitude projects”,”Backed by STP’s long India track record and Space Arc’s trained welding crews for supply-and-apply scope”],”limitations”:[“Not UV resistant — must always be covered by geotextile and screed or ballast, never left exposed”,”Weld quality is entirely operator-dependent; a poorly fused seam is the single most common failure point in any PVC liner”,”Non-reinforced construction means puncture and tear tolerance is lower than fabric-reinforced geomembranes, so the geotextile protection layers are not optional extras”,”Published data sheet lists a single 2 mm / 20 m roll format only, with no thinner or reinforced variant to choose from”,”Loose-laid systems make leak-tracing harder after the fact than a fully bonded membrane, since water can travel along the underside before finding a puncture”,”Higher material and skilled-labour cost than standard bituminous or cementitious waterproofing, so it’s rarely the right call for simple above-grade jobs”],”bestPractice”:”Treat the geotextile as part of the specification, not an optional add-on: ShaliGeo goes down first as a 50 mm-overlapped base layer, and a second layer goes over the laid PVC before any screed or backfill touches it. Grind the substrate smooth and clean before laying, provide a 75 mm radius cementitious coving at every vertical-to-horizontal junction, and keep overlap joints at a consistent 75 mm so the welding crew has a repeatable seam to fuse. Every weld should be checked on site — a needle test or vacuum box on a sample of joints catches a bad fusion before it’s buried under concrete. Terminate at parapets and upstands with the termination strip screwed at 300 mm centres, then seal that termination with water lock sealant topped with ShaliSeal PU; terminations, not the sheet field, are where most PVC liner leaks actually originate.”,”specs”:[{“property”:”Membrane type”,”value”:”Non-reinforced, opaque PVC geomembrane, twin-colour signal layer”},{“property”:”Thickness / roll size”,”value”:”2 mm; 2 m x 20 m roll”},{“property”:”Tensile strength (longitudinal & transverse)”,”value”:”≥ 16 N/mm²”},{“property”:”Elongation (longitudinal & transverse)”,”value”:”≥ 275%”},{“property”:”Tear strength”,”value”:”≥ 80 N/mm”},{“property”:”Puncture resistance”,”value”:”Static indentation L-2, dynamic indentation I-2″},{“property”:”Water pressure resistance”,”value”:”Waterproof at 6 bar / 72 hr”},{“property”:”Cold resistance”,”value”:”-20°C, no crack”},{“property”:”Root & oxidation resistance”,”value”:”Fulfilled”}],”useCases”:[{“sector”:”Metro & transit infrastructure”,”detail”:”Loose-laid over shotcrete or primary lining in cut-and-cover and NATM tunnel sections, welded joint by joint before the secondary concrete lining is cast.”},{“sector”:”Residential & commercial basements”,”detail”:”Sandwiched between two ShaliGeo geotextile layers under a multi-level basement raft slab in NCR high-rise projects with a high water table.”},{“sector”:”Water & sewage infrastructure”,”detail”:”Tanking underground water reservoirs, sumps and treatment tank structures where the 6 bar pressure rating covers sustained hydrostatic head.”},{“sector”:”Commercial roofs & podiums”,”detail”:”Laid beneath insulation and paver ballast in an inverted (protected membrane) roof build-up, kept permanently shielded from UV as the data sheet requires.”},{“sector”:”Retaining structures”,”detail”:”External tanking on diaphragm and blindside basement walls on riverside or low-lying NCR plots where ground water pressure is a known design load.”}],”faq”:[{“q”:”Is ShaliPVC the same thing as a PVC waterstop used at construction joints?”,”a”:”No. ShaliPVC is a full-sheet geomembrane liner that covers an entire tunnel, basement or roof surface. A PVC waterstop is a separate, narrower strip embedded across a specific construction or expansion joint. The two are often used on the same project but serve different roles.”},{“q”:”Can ShaliPVC be left exposed on a terrace or roof?”,”a”:”No. STP’s data sheet states it is not UV resistant, so it always has to be covered — by a geotextile and protection screed, insulation, ballast or paving — as part of the design, never left as a finished exposed surface.”},{“q”:”What thickness and roll sizes are available?”,”a”:”The published data sheet lists one format: 2 mm thickness in a 2 m x 20 m roll. If a project needs a different thickness or a reinforced variant, raise it with Space Arc before finalising the spec.”},{“q”:”How are the sheets joined on site?”,”a”:”By hot-air welding, with 75 mm overlaps in both directions at every joint. It is not glued or taped, and weld quality should be checked with a needle or vacuum test before the membrane is covered.”},{“q”:”How much water pressure can ShaliPVC actually withstand?”,”a”:”STP tests it as waterproof at 6 bar for 72 hours, which is roughly equivalent to a 60 metre head of water — comfortably beyond what most basement or tunnel water tables generate.”},{“q”:”Does Space Arc supply the membrane only, or install it too?”,”a”:”Both. As an authorised STP distributor and applicator, Space Arc supplies ShaliPVC, ShaliGeo and ShaliSeal PU as a matched system and can provide trained welding crews for the installation itself, not just the material.”}],”positioning”:”ShaliPVC sits inside a small STP family built for exactly this job: ShaliGeo geotextile as the mandatory protection layer on both faces, and ShaliSeal PU as the sealant used at every termination and penetration detail. For basement or roof work where cementitious or coating-based waterproofing would do the job at lower cost, STP’s ShaliCoat and ShaliCrete ranges are the more usual choice — ShaliPVC earns its place specifically where a fully welded, testable liner is needed, which in practice means tunnels, high water-table basements and protected roofs rather than routine terraces. Outside the STP range, the closest genuine alternative a specifier will weigh is Fosroc’s Proofex Engage, a pre-applied HDPE membrane that bonds mechanically into wet concrete rather than being loose-laid and welded — a reasonable substitute on blindside basement walls or fast-track jobs where a welding crew isn’t practical, at the cost of the repairability a loose-laid welded PVC system offers later in the structure’s life.”,”fosrocAlternative”:{“name”:”Proofex Engage”,”slug”:”fosroc-proofex-engage”,”note”:”Where the site logistics favour a pre-applied, concrete-bonded membrane over a welded loose-laid system — for example a blindside basement wall poured against sheet piling, or a fast-track job without a trained PVC welding crew — a specifier may choose Fosroc’s HDPE Proofex Engage instead, since it locks mechanically into the wet concrete as it cures.”}}

The technical insight

The number worth understanding on ShaliPVC’s data sheet is the 6 bar / 72 hr water pressure rating, roughly equivalent to a 60 metre static head, tested well beyond what most basement or tunnel water tables actually generate. The ≥275% elongation figure is the other one that matters in practice: PVC geomembranes need that stretch to absorb the differential movement that happens as concrete cures, settles and creeps around them without splitting at a weak point. Puncture resistance is reported as an indentation class (Static L-2, Dynamic I-2) rather than a raw force figure, which is standard for geomembranes and is exactly why the installation sequence sandwiches the sheet between geotextile layers on both sides — the membrane’s own puncture resistance is only ever the second line of defence, the geotextile cushion is the first. Because ShaliPVC is non-reinforced, it relies entirely on that protection detail; a reinforced, fabric-backed geomembrane trades some of the flexibility for higher intrinsic tear resistance and is the product to ask for if the cover system can’t be guaranteed.

Where it is used

• Metro, road and utility tunnel lining, cut-and-cover and NATM sections alike
• Basement raft slab and retaining wall tanking, sandwiched between two geotextile layers
• Underground water tanks, reservoirs and lift pit tanking below the water table
• Protected (inverted) roof and podium deck waterproofing under insulation and paver ballast
• Diaphragm wall and blindside basement wall lining before the internal concrete pour
• Car park and substructure waterproofing beneath paving in multi-level basements
• Cable and service tunnels where a fully welded, leak-testable liner is specified
• Termination and detailing at parapets, upstands and penetrations in combination with ShaliSeal PU

Key advantages

• Fully hot-air welded seams fuse into one homogeneous sheet rather than relying on adhesive lap bonding
• Welds can be needle or vacuum tested during installation, giving a verifiable seal before backfill
• ≥275% elongation absorbs minor substrate movement and settlement without the membrane splitting
• Verified to hold back water at 6 bar for 72 hours, suited to genuinely high water-table sites
• Root and oxidation resistant for a long service life once buried and covered
• Loose-lay application doesn’t demand a perfectly dry, primed substrate the way bonded membranes do
• Stays flexible down to -20°C with no cracking, useful on cold-store and high-altitude projects
• Backed by STP’s long India track record and Space Arc’s trained welding crews for supply-and-apply scope

Limitations & considerations

• Not UV resistant — must always be covered by geotextile and screed or ballast, never left exposed
• Weld quality is entirely operator-dependent; a poorly fused seam is the single most common failure point in any PVC liner
• Non-reinforced construction means puncture and tear tolerance is lower than fabric-reinforced geomembranes, so the geotextile protection layers are not optional extras
• Published data sheet lists a single 2 mm / 20 m roll format only, with no thinner or reinforced variant to choose from
• Loose-laid systems make leak-tracing harder after the fact than a fully bonded membrane, since water can travel along the underside before finding a puncture
• Higher material and skilled-labour cost than standard bituminous or cementitious waterproofing, so it’s rarely the right call for simple above-grade jobs

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliPVC

ShaliPVC sits inside a small STP family built for exactly this job: ShaliGeo geotextile as the mandatory protection layer on both faces, and ShaliSeal PU as the sealant used at every termination and penetration detail. For basement or roof work where cementitious or coating-based waterproofing would do the job at lower cost, STP’s ShaliCoat and ShaliCrete ranges are the more usual choice — ShaliPVC earns its place specifically where a fully welded, testable liner is needed, which in practice means tunnels, high water-table basements and protected roofs rather than routine terraces. Outside the STP range, the closest genuine alternative a specifier will weigh is Fosroc’s Proofex Engage, a pre-applied HDPE membrane that bonds mechanically into wet concrete rather than being loose-laid and welded — a reasonable substitute on blindside basement walls or fast-track jobs where a welding crew isn’t practical, at the cost of the repairability a loose-laid welded PVC system offers later in the structure’s life.

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