About STP ShaliUrethane LHM 2K 80

ShaliUrethane LHM 2K 80 belongs to STP Limited’s ShaliUrethane range of moisture-curing polyurethane waterproofing membranes, and it is the two-component, high-build member of that family. Component A (resin) and Component B (catalyst/hardener) are supplied pre-weighed in a 12.5 kg pack — 7.9 kg of A to 4.6 kg of B, a fixed 63:37 ratio by weight — and are machine-mixed on site just before application. That two-pack chemistry is what separates it from STP’s single-component ShaliUrethane LHM: the 2K version cures faster once mixed, builds a thicker, higher-solids film in fewer passes, and is the version STP positions for demanding exposed applications like bridge decks and podiums rather than routine terrace touch-ups. It carries ASTM C836 and ASTM C898 approvals, the two benchmarks Indian specifiers typically ask for on liquid-applied elastomeric membranes, and the TDS backs every physical property — elongation, tensile strength, crack bridging, adhesion — with the specific ASTM test method used.

For a Delhi NCR or Pan-India waterproofing contractor, what matters in practice is that this is a full waterproofing system, not a paint-and-forget coating. STP’s own methodology calls for surface prep with V-groove crack repair using ShaliCrete mortar, a primer coat (ShaliPoxy CTE 103 MI on concrete or ShaliPrime PUM), two coats of the membrane at roughly 980 gm/m² each with a 6-8 hour recoat window, an optional non-woven geotextile reinforcement layer for high-movement zones, a 36-hour final cure before any foot traffic, and a mandatory 7-day ponding test before the area is handed over. Skip any one of those steps and the membrane’s lab-tested numbers — 500% elongation, 4 MPa tensile strength, zero leakage under a 1-metre water column for 24 hours — won’t translate to what actually happens on a monsoon-exposed terrace three years later. Applied as the system is written, it’s a durable, UV-tolerant answer for roofs, podiums, retaining walls and pool shells that need to stay watertight while remaining exposed to sun and weather, not buried under a protective screed.

The technical insight

Two figures on the datasheet do the real explaining. First, 82±2% solids by weight — high for a liquid-applied membrane, and consistent with the “80” in the product’s name — which is why STP can hit a full 1000-1500 micron dry film in just two coats instead of the three or four thinner passes lower-solids membranes often need. Second, the pot life spec: 30±5 minutes for a 100 gm test batch, measured at 30°C/55% RH under ASTM D2471. That number matters more on an actual roof than in a lab, because real batches are bigger, ambient temperatures in North India routinely exceed 30°C, and pot life shortens as both go up — so a mixing and application plan that comfortably beats the datasheet’s 30-minute figure is what keeps a crew from fighting a partially-gelled batch on a hot terrace. The crack-bridging result (2 mm, ASTM C836 pass) paired with 500% elongation is also worth reading together rather than separately: elongation tells you the film can stretch, crack bridging tells you it can do that stretching across an active, moving joint without tearing at the edge — the property that actually matters when a slab hairline-cracks under thermal cycling six months after handover.

Where it is used

• Exposed RCC roofs and terraces subject to ponding, foot traffic and direct sun
• Podium decks over basements or parking, including areas later landscaped as terrace gardens
• Bridge decks and flyover surfaces ahead of wearing-coat or screed application
• Retaining walls and parapet upstands where a seamless, flexible seal is needed at movement joints
• Swimming pool shells and other water-retaining concrete structures
• Terrace gardens and planter boxes, where its root-resistant film protects the slab beneath soil and drainage media
• Balconies, chajjas and other weather-exposed RCC projections
• Metal decks, gutters and flashings where its bonding and anti-corrosive film protects the substrate

Key advantages

• Builds a genuine 1000-1500 micron dry film in just two coats (~980 gm/m² each) thanks to 82±2% solids — a full-bodied membrane, not a thin sacrificial coating
• 500±50% elongation at break combined with ASTM C836-passed crack bridging up to 2 mm lets it absorb slab movement and hairline cracking without rupturing the seal
• Verified hydrostatic resistance — no leak under a 1-metre water column for 24 hours — gives real confidence for pool shells and ponding-prone terraces
• UV resistant by design, so it can be left permanently exposed on roofs and podiums instead of needing a protective screed over it
• Strong, tested adhesion: 2.0-2.5 MPa on concrete (the concrete itself fails before the bond does) and 4.2-5.0 MPa on metal
• Cures to a seamless, blister-free monolithic film with no laps, seams or overlaps to fail, unlike sheet-applied membranes
• Wide service temperature range of -40°C to +100°C suits everything from a Delhi rooftop in June to below-parapet cold zones
• Compatible with a non-woven geotextile reinforcement layer where higher mechanical strength or added puncture resistance is needed

Limitations & considerations

• Short 30±5 minute pot life per 100 gm mix demands disciplined small-batch mixing and a fast application team, especially in Delhi NCR’s peak summer heat where working time shrinks further
• Substrate moisture must stay under 3% (5% ceiling right before application) — damp or recently cured concrete, common right after monsoon, will compromise the membrane if not given time to dry
• As an aromatic polyurethane, its grey colour will gradually mellow/yellow under prolonged UV exposure; STP is upfront that this doesn’t affect performance, but it’s a real cosmetic consideration for visible terraces
• Contains isocyanate and is flammable — requires PPE (gloves, goggles, dust mask), good ventilation, and careful on-site storage; not a product for untrained DIY application
• Narrow application window of +10°C to +40°C substrate and ambient temperature, and no application if rain is imminent, which constrains scheduling during North India’s monsoon and can occasionally pinch cold winter mornings too
• Correct dry film thickness depends entirely on applicator discipline (coat weight, spray technique, optional geotextile placement) — under-applying it defeats the tested performance figures on the datasheet

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliUrethane LHM 2K 80

Within STP’s own range, LHM 2K 80 sits alongside single-component ShaliUrethane LHM — pick the 1K version for smaller, simpler jobs where you’d rather avoid the two-pack mixing and short pot life, and the 2K 80 for larger, higher-spec exposed decks (podiums, bridge decks) where the extra film build and faster cure pay off. It’s designed to work inside a system: prime with ShaliPoxy CTE 103 MI or ShaliPrime PUM, repair cracks and honeycombing with ShaliCrete mortar and ShaliSBR Latex bond coat, and where the deck will see sustained foot traffic or abrasion, cap it with a ShaliProtek PU HA protective topcoat. Against the wider market, its natural comparison is Fosroc’s Nitoproof line — Nitoproof 600 competes more directly on exposed-roof, single-component turf, while Fosroc’s genuine two-component PU chemistry, Nitoproof PU2000, is built for buried/below-grade tanking rather than sun-exposed decks (see the honest caveat below). Specifiers choosing between STP and Fosroc for an exposed terrace or podium are usually weighing this against Nitoproof 600 or similar aromatic-PU liquid membranes on tensile strength, crack-bridging figures and each brand’s local application support in Delhi NCR.

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