STP ShaliTPO PR
A polyester-reinforced TPO membrane built for hot-air-welded, leak-free roofs that also knock the summer heat load down.
What is it?
A single-ply thermoplastic polyolefin (TPO) roofing membrane internally reinforced with a polyester scrim, supplied in 1.2 mm and 1.5 mm gauges with a factory-finished, high-reflectance top surface.
Where is it used?
Exposed RCC, metal and wooden roof decks, terrace gardens and green roofs, podium/plaza decks, and industrial shed roofs across Delhi NCR and pan-India construction and re-roofing projects.
Why use it?
Seams are fused by hot-air welding rather than glued or torched, so the roof ends up as one continuous, monolithic sheet with a documented SRI of 100 and a -30 degrees C to 100 degrees C service window, resisting ponding, UV, ozone and even root penetration.
How is it applied?
A ShaliGeoText separation layer is loose-laid first, the ShaliTPO PR sheet is rolled out and mechanically fastened to the deck at a fixing density set by local wind-uplift conditions, and the overlaps (75-125 mm) are hot-air welded; parapet terminations get a termination strip, sealant and a ShaliSeal PU GG top seal.
About STP ShaliTPO PR
ShaliTPO PR comes from STP Limited, the Delhi-headquartered construction chemicals major that has been supplying bitumen, waterproofing and coating systems to Indian infrastructure for over eight decades. Within STP’s ShaliTPO family, the PR designation stands for polyester-reinforced: an internal polyester scrim is sandwiched inside the thermoplastic olefin sheet, which is what separates it from the plainer ShaliTPO HG (a homogeneous, non-reinforced variant more suited to protected or ballasted applications). That scrim is the whole point of an exposed, mechanically fastened roof membrane — it is what lets the sheet carry point loads at the fastener plates and resist wind-uplift stress over years of thermal cycling without the sheet tearing outward from a fastener washer.
What actually distinguishes a TPO system like this from the bituminous and PVC membranes it competes against in the Indian market is the weld. Every overlap is fused with hot air rather than a torch flame or a contact adhesive, so once installed the roof is effectively one continuous polymer sheet rather than a series of bonded joints that can eventually peel. STP backs that with a reflective top surface engineered to a Solar Reflectance Index of 100, which is a genuine, measurable cool-roof credential rather than a marketing claim — relevant on Delhi NCR industrial sheds and terraces where roof-surface temperature swings drive both cooling load and membrane fatigue. It is also chlorine, plasticizer and phthalate free, which matters on projects chasing green-building points and on installations where PVC’s plasticizer migration over a hot Indian summer is a known long-term liability.
The technical insight
The STP data sheet benchmarks ShaliTPO PR against ASTM D6878, the standard TPO membrane specification, and the numbers explain why the reinforced grade costs more than the homogeneous ShaliTPO HG. Grab breaking strength comes in at 225 lbf minimum on the 1.2 mm sheet and 230 lbf minimum on the 1.5 mm sheet (typical values run to 250-260 lbf), well above the ASTM floor of 220 lbf, while tearing strength sits at 55 lbf minimum against a 55 lbf standard requirement — the scrim is doing real mechanical work, not just padding a spec sheet. Puncture resistance under FTM 101C is 250 lbf on the thinner gauge and 300 lbf on the 1.5 mm sheet, which is the number that actually matters for a mechanically fastened roof carrying foot traffic during maintenance.
Two other figures are worth reading carefully before specifying. Water vapour permeance is capped at 0.10 perms (ASTM E96), which classifies the membrane as an effective vapour barrier — fine for most Indian roof decks but a factor to flag if the design calls for a vapour-permeable assembly underneath insulation. And the weathering figure, over 21,600 kJ/(m2.mm) against an ASTM floor of 10,080 under ASTM G155, plus a documented pass on ozone resistance at 100 pphm for 168 hours, is what supports leaving the sheet permanently exposed to Indian sun and pollution loads rather than requiring a protective overburden — something a plain bituminous membrane cannot claim without a screed or paver layer on top.
Where it is used
- Exposed RCC terrace and flat-roof waterproofing on residential, commercial and institutional buildings
- Retrofit waterproofing over existing metal roof sheeting on industrial and warehouse sheds
- Wooden roof deck waterproofing where a lightweight, mechanically fixed membrane is preferred over wet-applied systems
- Terrace gardens and green roofs, using the membrane’s root-resistance rating as the waterproofing layer under growing media
- Podium decks, plaza decks and parking-deck waterproofing in mixed-use and high-rise developments
- Cold storage, FMCG warehouses and logistics parks, where the SRI 100 surface reduces roof-driven cooling load
- Institutional and campus buildings (schools, hospitals) needing a low-maintenance, leak-free roof over a long service life
- Re-roofing over aged bituminous or built-up roofing where tear-off is impractical and a new mechanically fastened layer is preferred
Key advantages
- Hot-air-welded seams fuse into a single continuous sheet instead of relying on adhesive or torch bonding at every joint
- Polyester scrim reinforcement gives markedly higher breaking, tearing and puncture resistance than the non-reinforced ShaliTPO HG
- SRI 100 reflective surface genuinely lowers roof-surface and under-deck temperatures, cutting summer cooling load
- Rated for continuous service from -30 degrees C to 100 degrees C without cracking, tearing or brittleness
- Chlorine-free, plasticizer-free and phthalate-free, avoiding the long-term plasticizer migration issue seen in PVC membranes
- Root-resistant, so the same membrane can double as the waterproofing layer under a green roof or terrace garden
- Dry, mechanically fastened installation avoids naked-flame torching and open-tank hot bitumen on site
- Field-repairable — damaged sections can be patched with a fresh hot-air weld rather than a full re-lay
Limitations & considerations
- Requires a hot-air welding machine and a trained applicator; a poorly fused seam is a real leak risk, not a cosmetic issue
- Mechanical fastening means the deck must accept anchors at engineered spacing — not ideal where penetrations into the structural slab are restricted
- Low vapour permeance (0.10 perms max) makes it effectively a vapour barrier, which needs to be accounted for in the roof build-up design
- Exposed installation still needs periodic inspection of seams, terminations and fastener plates; it is not a fit-and-forget system
- Not intended for permanently submerged or hydrostatically loaded conditions such as water tanks — that is a different STP product line
- Light-coloured reflective surface can pick up visible dust and pollution staining in dense urban sites and benefits from occasional cleaning
Selection & best practice
Get the substrate right before the membrane ever comes off the roll: the deck needs to be free of loose aggregate, oil and sharp debris, with a 75 mm cementitious coving at every vertical-to-horizontal junction so the membrane isn’t bent over a sharp corner. Always run the ShaliGeoText 300 GSM separation layer first — it protects the membrane underside from the deck and lets the sheet move independently during thermal cycling. Fastener density is not a fixed number; it has to be set against the site’s design wind velocity, so get STP’s technical team or an experienced applicator to size it rather than defaulting to a standard spacing. Every hot-air weld should be checked with a probe test on cooling, and parapet terminations need the termination strip screwed at 300 mm centres with sealant behind it and ShaliSeal PU GG on top — terminations, not the field membrane, are where most TPO roofs actually leak.
Specifications
| Membrane type | Reinforced TPO (thermoplastic polyolefin), polyester scrim, single-ply |
| Nominal thickness | 1.2 mm +/-10% or 1.5 mm +/-10% (ASTM D751) |
| Breaking strength (Grab, MD/TD) | 225 lbf min / 230 lbf min, typical 250-260 lbf (ASTM D751) |
| Elongation at break | 15% min (MD), 25% typical (TD) (ASTM D751) |
| Tearing strength | 55 lbf min, 70 lbf typical (ASTM D751) |
| Puncture resistance | 250 lbf (1.2 mm) / 300 lbf (1.5 mm) (FTM 101C) |
| Water vapour permeance | 0.10 perms max (ASTM E96, Procedure B) |
| Solar Reflectance Index / Reflectivity | SRI 100; Reflectivity 0.79 (ASTM C1549); Emissivity 0.909 (ASTM C1371) |
| Service temperature & pack size | -30 degrees C to 100 degrees C continuous; rolls 2 m width x 20 m length |
Industry use cases
Industrial sheds & warehousing (Delhi NCR)
Mechanically fastened retrofit over ageing metal roof sheeting, using the SRI 100 surface to cut shed floor temperatures and roof-driven cooling load.
Corporate and IT campus terraces
Exposed RCC terrace waterproofing left permanently visible, relying on the membrane’s UV and ozone resistance instead of a protective screed.
Residential high-rise podiums and terrace gardens
Root-resistant membrane laid beneath planters and landscaped decks where a conventional bituminous membrane would need extra root-barrier protection.
Cold storage and FMCG distribution centres
Wide -30 degrees C to 100 degrees C service range and reflective surface suit large-span roofs carrying both thermal cycling and solar load.
Institutional campuses (schools, hospitals)
Hot-welded, low-maintenance roofing preferred where recurring re-coating or bituminous re-application isn’t practical on an active campus.
Frequently asked questions
What does the ‘PR’ in ShaliTPO PR actually mean?
Does ShaliTPO PR need a torch or adhesive to install?
Should I choose the 1.2 mm or the 1.5 mm gauge?
Can it go directly on an RCC terrace, or does it need a base layer?
Is it suitable for a green roof or terrace garden?
How is it repaired if punctured on site?
How we position STP ShaliTPO PR
Within STP’s own ShaliTPO range, PR is the mid-tier, mechanically fastened workhorse: step down to ShaliTPO HG for a lighter, non-reinforced sheet in protected or ballasted assemblies, or step up to ShaliTPO PR FB (fleece-backed, for fully bonded/adhered installs) or ShaliTPO GR FB (glass-reinforced fleece-backed, for the highest tensile demands) depending on the fixing method the roof actually calls for. For below-grade or podium waterproofing where a torch-applied bituminous membrane is the preferred technology rather than an exposed single-ply sheet, Fosroc’s Proofex Torchseal is a credible alternative worth comparing on the same project. Internationally, ShaliTPO PR sits in the same category as Sika Sarnafil and GAF/Firestone TPO membranes; the ASTM D6878 benchmarking on STP’s data sheet is what lets a specifier compare it against those directly on the same test methods rather than on marketing claims alone.
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