STP SuperThermoLay
STP’s torch-applied bituminous membrane range — APP for heat-stable exposed roofs, SBS for cold-flexible basements and moving structures — engineered for the extremes Indian construction actually throws at a deck.
What is it?
A range of factory-made, torch-applied bituminous sheet membranes reinforced with non-woven polyester, offered in APP (heat-stable) and SBS (cold-flexible) polymer chemistries.
Where is it used?
Exposed and protected roofs, terraces, podium decks, basements, car parks, bridges, tunnels and water-retaining structures across India.
Why use it?
It gives specifiers a matched pair of chemistries — one built to resist flow on hot exposed decks, one built to stay elastic through movement and cold — instead of a single one-size-fits-all bitumen sheet.
How is it applied?
Rolled over a primer-coated, cured substrate and heat-fused with an LPG torch until the surface embossing melts, with overlaps sealed by an extruded bitumen bead at every lap.
About STP SuperThermoLay
SuperThermoLay is STP Limited’s range of prefabricated, torch-applied bituminous waterproofing membranes, built around two proven polymer chemistries: APP (atactic polypropylene), which raises the softening point above 150°C for exposed roofs baking under Indian summer sun, and SBS (styrene-butadiene-styrene), which keeps the sheet elastic down to roughly -15°C for basements, podiums and any deck that moves. Both grades share the same underlying idea: a factory-controlled sheet, reinforced with a non-woven polyester mat, that is rolled out and heat-fused to a primed substrate with an LPG torch rather than mixed and troweled on site. That single manufacturing discipline is what buyers are really paying for compared with liquid-applied systems — a membrane whose thickness, tensile strength and elongation are fixed at the factory, not at the mercy of a site crew’s dosing.
Where the range earns its keep in practice is the choice it gives a specifier. A hot, sun-exposed terrace in Delhi NCR that never sees frost has no use for sub-zero flexibility; it needs a compound that will not soften and slump at high deck temperatures, which is exactly what the APP grade is built for. A basement raft slab, a bridge deck, or a hill-station roof, on the other hand, lives with constant movement and sometimes near-freezing nights, and that is where the SBS grade’s rubber-like recovery earns its keep. STP also fields specialised SuperThermoLay variants — including fire-retardant and low-temperature grades — for projects with tighter compliance needs. Space Arc, as an authorised STP distributor and applicator across Delhi NCR and Pan-India, stocks both core grades and helps project teams work out which one actually fits the deck in question, rather than defaulting to whichever is easier to source that week.
The technical insight
The two grades exist because bitumen on its own is a poor performer at either end of the thermometer: plain oxidised bitumen softens and creeps in heat, then turns brittle and cracks in cold. Polymer modification fixes one end or the other, not both, which is why STP offers two distinct compounds rather than a single compromise blend. APP (atactic polypropylene) builds a semi-crystalline plastic network into the bitumen that lifts the softening point past 150°C and gives the sheet no-flow behaviour under sustained heat — exactly the failure mode that matters on an exposed Delhi terrace at high summer deck temperatures. SBS (styrene-butadiene-styrene) does the opposite: its rubbery mid-block gives the compound genuine elastic recovery, so it stays workable and torchable in cold weather and springs back rather than tearing when a slab expands and contracts through a day-night cycle. In both cases the non-woven polyester reinforcement is what actually carries the tensile load and lets the sheet bridge shrinkage cracks; the polymer decides how the compound behaves at temperature extremes, while the polyester decides how much load and movement the sheet can absorb before it splits.
Where it is used
- Exposed terrace and flat-roof waterproofing on residential, commercial and industrial buildings
- Protected roofing under screed, tiles or paver finishes as a single-layer system
- Podium decks and landscaped roof gardens over habitable basements or car parks
- Basement rafts, retaining walls and other below-grade tanking exposed to ground water
- Bridge decks, tunnels and metro structures needing a movement-tolerant barrier
- Swimming pools and water-retaining structures such as tanks and reservoirs
- Damp-proofing courses over foundations and plinth beams
- Cold-climate and hill-station roofing where sub-zero flexibility matters (SBS grade)
Key advantages
- Two purpose-built chemistries in one family — APP for hot exposed decks, SBS for cold or movement-prone structures — instead of one compromise blend
- Factory-controlled thickness, tensile strength and elongation, removing the batch-to-batch variability of site-mixed liquid coatings
- Instantly waterproof once torched, with no curing wait before the next trade can move onto the roof
- Non-woven polyester reinforcement bridges shrinkage cracks and carries structural movement without splitting
- Heat-welded overlaps fuse individual rolls into one continuous, monolithic barrier rather than a jointed system
- Both grades conform to ASTM D 5147 and IS 16532:2017, clearing third-party specs on government and institutional tenders
- Slate/mineral-finish options available for exposed roofs that need a built-in UV-stable wearing surface
- Backed by a documented STP system (ShaliTex primers, sealants, reflective top-coats) rather than a standalone sheet
Limitations & considerations
- Torch application demands a trained crew and open LPG flame; it isn’t a DIY or unsupervised-labour job
- Open-flame work carries fire-safety obligations and is unsuitable near gas lines, combustibles or confined unventilated spaces
- Substrate must be cured, dry and properly graded before laying, or blistering and debonding follow
- Watertightness is largely workmanship-dependent — a poorly welded lap is a direct leak path regardless of membrane quality
- Choosing the wrong grade (APP where SBS was needed, or vice versa) undermines the whole point of having two chemistries
- Complex penetrations and tight detailing are handled less gracefully than with a liquid-applied membrane
Selection & best practice
Picking the right grade is step one: default to APP for exposed, sun-baked roofs and to SBS for basements, podiums, bridge decks or any application where the structure moves or the site runs cold. After that, success is decided at the substrate, not the membrane. New concrete needs a full 28-day cure, mechanical abrasion to remove laitance, and moisture content confirmed below 5% before priming. Build the correct fall so water actually drains, keep drain mouths recessed below deck level, and form proper coving at every upstand with polymer-modified mortar. Prime with STP’s ShaliTex Primer and let it go tack-free before torching; heat both the primed deck and the membrane underside only until the surface embossing disappears, then press the roll forward so a continuous bitumen bead extrudes at every lap — overheating past the smoking point degrades the compound. Keep end laps and side laps to spec, envelope the whole roof parapet-to-parapet, seal edges into grooves with a compatible sealant, and finish exposed non-trafficable areas with a reflective coat or protect trafficable zones with a screed. Work only in dry weather within the product’s stated temperature window, and never treat torch application as a job for an untrained crew — poor lap welding is the single most common cause of callbacks on bituminous membrane roofs.
Specifications
| Membrane technology | Torch-applied, polymer-modified bituminous sheet membrane (APP or SBS grade) |
| Reinforcement core | Non-woven, spun-bonded polyester mat (approx. 140-160 g/m² depending on grade) |
| Thickness range | 2 mm to 5 mm depending on grade and application |
| Roll width | 1 m, in standard roll lengths of 10-15 m depending on thickness |
| Softening point (APP grade) | ≥150°C, tested to IS 1205 / ASTM D 36 |
| Low-temperature flexibility (SBS grade) | Down to approx. -15°C |
| Tensile strength (longitudinal) | Roughly 300-800 N/5 cm depending on grade, per ASTM D 5147 / IS 13826 |
| Governing standards | ASTM D 5147; IS 16532:2017 (Indian standard for polymer-modified bitumen membranes) |
| Application method | LPG-torch heat fusion onto a primed substrate; no site mixing required |
Industry use cases
Commercial and institutional roofs
Large exposed terraces on offices, malls and hospitals in the APP grade, where the high softening point prevents slump under peak summer heat and a slate finish can double as the wearing surface.
Residential terraces
Single-layer torch-on waterproofing on independent houses and apartment roofs, enveloped parapet-to-parapet and protected with a screed for long-term leak-free service.
Basements and car parks
Below-grade tanking of raft slabs and retaining walls in the SBS grade, where malleability at corners and resistance to ground-water salts suit hydrostatic exposure.
Infrastructure
Bridge decks, tunnels and metro structures needing a movement-tolerant, standards-compliant membrane that carries slab thermal cycling without splitting.
Podiums and roof gardens
Landscaped decks over habitable basements or parking, where either grade forms the waterproof layer beneath drainage and planting build-ups depending on movement and exposure.
Frequently asked questions
What’s the actual difference between the APP and SBS versions of SuperThermoLay?
Which grade should I specify for a Delhi NCR terrace?
Does SuperThermoLay need a primer before torching?
Is torch-applied membrane safe to install on an occupied building?
What thickness of SuperThermoLay do I need?
Can SuperThermoLay be left exposed without a protective screed?
How we position STP SuperThermoLay
SuperThermoLay is STP’s torch-applied membrane family, split into two grades that specifiers should treat as siblings rather than interchangeable options: SuperThermoLay APP for exposed, heat-loaded roofs, and SuperThermoLay SBS for basements, podiums and structures with ongoing movement or cold exposure — see the dedicated APP and SBS pages for full technical data sheets. STP also offers fire-retardant and low-temperature variants within the same range for projects with tighter compliance needs. Pair either grade with STP’s own system consumables — ShaliTex Primer as the bond coat, a compatible sealant at edges and grooves, and a reflective top coat for exposed non-trafficable roofs. For below-grade tanking on basements, podiums and tunnels where aggressive ground conditions dominate, some consultants specify Fosroc’s Proofex Torchseal range instead; Space Arc supplies and applies both STP and Fosroc, so the choice can follow the spec rather than the shelf.
Fosroc Proofex Torchseal 3P & 4P — A specifier working below grade — basements, podiums or tunnels with aggressive ground exposure — may prefer Fosroc’s Proofex Torchseal range, which is built around tanking performance rather than hot exposed-roof service.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.