About STP ShaliUrethane BTD I

ShaliUrethane BTD I is the improved grade in STP’s well-known BTD family of water-based polyurethane waterproofing membranes. Like the standard BTD, it is a single-component, cold-applied, fibre-reinforced elastomeric liquid that is simply stirred and applied by brush or roller — no primer-heavy epoxy systems, no torch, no hot works. What sets the coating apart is that it is water-based rather than solvent-based: VOC content is effectively nil, it has almost no odour, and it can be laid on slightly damp concrete, which is a real advantage on Indian sites where decks rarely dry out fully between monsoon showers. Once cured it forms a genuinely seamless, monolithic skin over the whole surface, so there are no laps or joints to fail the way they do with sheet membranes.

The “I” (improved) designation reflects STP’s refinements to the base chemistry for better extensibility and film performance, while keeping the same easy field workflow that contractors already know. The membrane conforms to ASTM C 836 and ASTM D 6083-97a — the recognised international standards for liquid-applied and acrylic roof coatings — and carries meaningful elongation, crack-bridging and adhesion figures that let it move with the substrate instead of cracking with it. Space Arc Engineering supplies BTD I as an authorised STP distributor across Delhi NCR and pan-India, and our applicators can execute the full system, from surface repair and coving through to the ponding test.

The technical insight

The performance of BTD I comes from its elastomeric polyurethane binder. As the water phase evaporates, the polymer coalesces into a continuous rubbery film with high elongation (ASTM D 2370, around 350 percent) and good elastic recovery — so when a concrete deck expands in the afternoon heat and contracts at night, or when a shrinkage crack up to 2.5 mm opens beneath it, the membrane stretches and bridges the movement rather than tearing. Because it is a liquid that self-levels into every pore and corner, adhesion to primed concrete is high (pull-off failure occurs in the concrete itself, not at the bond line), which stops water from tracking sideways under the film — the classic failure mode of loosely-laid sheet systems. The embedded fibre and optional geo-tissue reinforcement add tensile stability across wider cracks, while the film stays breathable, letting residual slab moisture escape as vapour instead of blistering the coating. In the white grade, the same film also reflects solar radiation (SRI 109), so it cools the slab beneath and slows the thermal cycling that ages any roof coating.

Where it is used

• Waterproofing of exposed RCC roof slabs and terraces on residential, commercial and institutional buildings
• Sloped roofs and non-trafficable roofs where a seamless, self-finished membrane is wanted without a separate screed
• Refurbishment and over-coating of aged APP / SBS / tar-felt roofs that have started to leak
• Podium decks and over-decks that will later receive a protective screed or tile finish
• Gutter, valley and box-gutter waterproofing where sheet membranes are hard to lap
• Corrugated and profiled roofs needing a cold-applied, jointless coat
• Cool-roof applications using the white grade for solar reflectance and heat reduction
• Parapet upturns and skirtings, terminated into a groove for a fully sealed detail

Key advantages

• Water-based with nil VOC and low odour — safe for occupied buildings and confined roofs
• Single-component and cold-applied: just stir and roller/brush, no mixing ratios, no torch, no hot works
• Forms a truly seamless, monolithic membrane with no laps or joints to fail
• Can be applied on slightly damp concrete, cutting weather-window delays on Indian sites
• High elongation and crack-bridging (up to 2.5 mm) let it move with the structure
• Excellent adhesion to primed concrete — pull-off failure occurs in the concrete, not the bond
• UV-stable and breathable, so it can be left exposed and won’t blister over residual slab moisture
• White grade offers SRI 109 for cool-roof energy savings

Limitations & considerations

• Not a wearing surface — foot or vehicle traffic needs a protective screed, tiles or a PU top-coat such as ShaliProtek PU HA
• Application temperature must be above 5 degrees C, and standing water or ponding must be avoided during application and cure
• Being water-based, it should not be applied when rain is imminent until it has touch-dried and cured
• Full curing takes about 7 days, and the confirming ponding test should only be run after 14 days at ambient temperature
• Metal/profiled roofs need a DTM-type primer specified by STP’s technical cell rather than the standard concrete primer
• As a coating it depends heavily on surface preparation, crack repair and correct film build — under-application (thin coats) will compromise the DFT and performance

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliUrethane BTD I

Within the STP range, BTD I is the improved water-based PU membrane; specifiers wanting the fibre-reinforced anti-algae base grade can use standard ShaliUrethane BTD, while a trafficable wearing coat over it is best handled by ShaliProtek PU HA. The system’s own ancillaries — ShaliPrime WB primer, ShaliCrete and ShaliSBR Latex for crack repair and coving, ShaliPlast IW integral waterproofer, and ShaliGeoText geo-textile for protection — round out a complete STP roof package. Where a client prefers a cementitious, tanking-style approach for basements, water tanks or below-grade masonry, we cross-sell into Fosroc’s Brushbond range as a complementary option rather than a like-for-like swap. Space Arc supplies all of these as an authorised distributor and applicator across Delhi NCR and pan-India.

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