STP ShaliTPO PR FB
A polyester-reinforced, fleece-backed TPO membrane that hot-air welds into one continuous waterproof sheet — built for exposed terraces that see peak Delhi summer heat and monsoon standing water.
What is it?
A 1.2 mm or 1.5 mm single-ply thermoplastic polyolefin (TPO) roofing membrane reinforced with a polyester scrim and finished with a fleece backing, designed to be hot-air welded at the seams into a single monolithic waterproof sheet.
Where is it used?
Exposed RCC, metal and wooden terraces, podium and parking decks, green/landscaped roofs, and below-ground blindside applications where root resistance and long-term chemical exposure matter.
Why use it?
Delivers a factory-controlled, defect-tolerant waterproofing layer — high tensile and puncture strength, a highly reflective surface that keeps the roof cooler, and welded (not adhesive) seams that don’t rely on site-mixed chemistry to cure correctly.
How is it applied?
Loose-laid over a ShaliGeoText 300 GSM separation layer, mechanically anchored at the field and perimeter per the site’s wind-uplift requirement, then hot-air welded at 75-125 mm overlaps; parapet terminations are strip-fixed and sealed with ShaliSeal PU GG.
About STP ShaliTPO PR FB
STP’s ShaliTPO PR FB belongs to a different waterproofing family from the cementitious coatings, PU membranes and bitumen sheets that dominate Indian terrace work. Thermoplastic polyolefin (TPO) is a single-ply, factory-extruded sheet — here reinforced internally with a polyester scrim for tensile and tear strength, and given a non-woven fleece backing on the underside so it can be loose-laid over a separation layer and mechanically fixed rather than fully bonded with adhesive. Where an APP or SBS bitumen membrane depends on a correctly heated torch pass and a liquid PU depends on correctly mixed, correctly cured chemistry on-site, ShaliTPO’s seams are hot-air welded — the same TPO material on both sheets is fused into one continuous polymer, which is far less dependent on ambient weather or applicator skill on the day of laying than solvent or heat-torch bonding.\n\nFor the Delhi NCR market specifically, the two properties that matter most are UV/solar performance and thermal range. ShaliTPO PR FB carries continuous serviceability from -30°C to 100°C without cracking or embrittlement, and its light-coloured, highly reflective surface cuts the heat load a black bitumen terrace would otherwise absorb through a Delhi summer — a genuine cool-roof effect rather than a marketing claim, since it’s measured against UNI EN 1297 weather-resistance and cold-bending standards. Combined with root resistance (DIN 4062) it’s also one of the few sheet systems STP offers that can legitimately sit under a landscaped or green roof, or go below grade on a blindside wall, without a separate root barrier.
The technical insight
The “PR FB” designation tells the whole engineering story. PR is the polyester-scrim reinforcement that gives the sheet its structural numbers — 1100 N/5cm minimum tensile strength and 300 N minimum tear strength (UNI EN 12311-2 / EN 12310-2) — roughly double what STP’s unreinforced ShaliTPO HG homogeneous sheet carries in the same thickness, which is why PR and PR FB are specified for traffic-bearing or mechanically-fastened roofs rather than fully-bonded ones. FB is the fleece backing, a non-woven layer laminated to the underside that lets the sheet be loose-laid and mechanically anchored (rather than solvent- or torch-bonded to the deck) and gives ballast or paver protection a cushioned interface instead of bare TPO-on-concrete abrasion. The hot-air welded seam is the other differentiator worth understanding: peel resistance of 150 N/50mm minimum and shear tested to “breaking out of joints” (UNI EN 12316-2 / EN 12317-2) means the weld is engineered to be stronger than the sheet itself — if a lap ever fails under load, the membrane tears before the seam does, which is the opposite failure mode of a poorly torched bitumen lap.
Where it is used
- Exposed flat RCC terrace waterproofing on new-build residential and commercial roofs
- Retrofit over aging, cracked bitumen or acrylic waterproofing without full removal of the old layer
- Metal deck roofing on industrial sheds, warehouses and factory buildings
- Podium and parking-deck waterproofing under paver or landscape finishes
- Green/landscaped roof waterproofing where root resistance is mandatory
- Below-ground blindside waterproofing on basement walls needing chemical and root resistance
- Cold storage and food-processing plant roofs where a chemically inert, easy-to-clean surface is required
- Institutional and commercial buildings targeting cool-roof or IGBC green-building credits
Key advantages
- Hot-air welded seams fuse into one continuous sheet, tested to fail by tearing the membrane before the joint opens
- High tensile (1100 N/5cm) and tear strength (300 N min) for wind-uplift zones and foot/plant-room traffic
- Highly reflective surface lowers roof surface temperature — a genuine cool-roof benefit through Delhi’s summer
- Chlorine-, plasticizer- and phthalate-free construction, relevant where rainwater is harvested off the roof
- Root-resistant per DIN 4062, so it can go under green roofs or landscaped decks without a separate barrier
- Rated for continuous service from -30°C to 100°C with cold bending to -40°C, covering north-India’s full seasonal swing
- Field-repairable by re-welding a patch if the membrane is later punctured
- 85-year-old Indian manufacturer with pan-India TDS support and an established applicator network
Limitations & considerations
- Hot-air welding is a skilled trade — inconsistent weld temperature or overlap produces the one failure mode this system is otherwise designed against, so applicator training matters more than with liquid-applied systems
- Mechanical fastening pattern must be engineered to the site’s wind-uplift zone; loose-laying without adequate anchoring is not a substitute for a proper fixing schedule
- Like any sheet membrane, performance lives or dies at drain outlets, pipe penetrations and parapet terminations — detailing quality matters as much as the membrane itself
- Exposed white/light TPO can pick up dust and algae staining in humid, low-maintenance settings, gradually reducing the reflectance advantage without periodic cleaning
- Available only in 1.2 mm and 1.5 mm thicknesses and a fixed 2 m x 20 m roll size, so irregular roof geometries need careful cutting-plan and wastage allowance
- Higher upfront material and skilled-labour cost than conventional brick-bat-coba or cementitious coatings, though it is usually offset over the membrane’s service life
Selection & best practice
Grind or jet-clean the deck free of loose aggregate, oil and sharp protrusions before laying, and form a 75 mm cementitious coving at every vertical-to-horizontal junction so the membrane isn’t asked to bend sharply at corners. Roll out ShaliGeoText 300 GSM as a loose separation layer with 50 mm overlaps first, then lay ShaliTPO PR FB over it and mechanically anchor it with plates sized and spaced for the site’s actual wind-uplift exposure — this is a structural calculation, not a fixed spacing, and should be signed off by the applicator before welding begins. Weld overlaps at 75-125 mm using hot air only (never a naked flame on TPO), and probe-test a sample of completed seams with a blunt tool to confirm full fusion before covering or handing over. Terminate at parapets with a termination strip screwed at 300 mm centres, seal the back of the strip with a water-lock sealant and finish on top with ShaliSeal PU GG — this termination detail is the single most common leak point on TPO roofs when skipped or rushed, so Space Arc supervises it directly on every install we execute.
Specifications
| Chemistry / system | Thermoplastic polyolefin (TPO), polyester scrim reinforced, fleece backed (FB) |
| Thickness | 1.2 mm ±10% or 1.5 mm ±10% (UNI EN 1849-2) |
| Specific weight | 1.32 kg/m² (1.2 mm) / 1.62 kg/m² (1.5 mm), UNI EN 1849-2 |
| Tensile strength | 1100 N/5cm min (UNI EN 12311-2) |
| Elongation at break | 15% min (UNI EN 12311-2) |
| Tearing strength | 300 N min (UNI EN 12310-2) |
| Puncture resistance | 400 mm min (DIN 16726-5.12) |
| Service / cold-bend range | Continuous service -30°C to 100°C; cold bending ≤ -40°C (UNI EN 495-5) |
| Roll / pack size | 2 m width x 20 m length; supplied in 1.2 mm and 1.5 mm thickness |
Industry use cases
Residential terrace retrofit, Delhi NCR
Re-waterproofing an aging, cracked bitumen terrace where the client wants a welded single-ply system rather than another coating that will crack again in a monsoon-summer cycle.
Industrial / warehouse roofing
Metal-deck sheds where a mechanically fixed, wind-rated membrane is needed over large uninterrupted roof spans.
Podium deck, residential complex
Waterproofing under a landscaped podium deck where root resistance and paver-protection fleece backing are both required.
Institutional building, cool-roof target
Schools or offices specifying a reflective roof surface to cut cooling load and support an IGBC or green-building submission.
Basement / blindside wall
Below-ground waterproofing where chemical exposure and root ingress from adjacent soil both need to be resisted.
Frequently asked questions
What does the “PR FB” in the name actually mean?
Can this go over our existing old waterproofing without stripping it off first?
Does installation need special machinery?
Is it safe for a terrace that gets regular foot or plant-room traffic?
How long does it last, and is there a warranty?
How does the cost compare to brick-bat-coba or a bitumen membrane?
How we position STP ShaliTPO PR FB
ShaliTPO PR FB sits in the reinforced, traffic-rated tier of STP’s own TPO family — it’s a step up from the unreinforced ShaliTPO HG / HG FB homogeneous sheets, sits alongside the non-fleece ShaliTPO PR for fully-adhered applications, and below the glass-reinforced ShaliTPO GR FB where even higher dimensional stability is needed. Within Space Arc’s broader waterproofing range, it’s the specify-this-when-you-want-a-welded-single-ply-membrane option, distinct from Fosroc’s Proofex range: Proofex Engage is a preformed HDPE studded sheet built mainly for below-grade blindside tanking rather than exposed hot-welded roofing, and Proofex 3000 is a self-adhesive bituminous membrane rather than a true TPO — so a specifier choosing between the two brands is usually deciding between STP’s welded-TPO approach and Fosroc’s adhesive/torch-applied bituminous or HDPE systems, not comparing like-for-like products. Where a project genuinely needs a heat-welded single-ply roof membrane, ShaliTPO PR FB remains the more direct fit in Space Arc’s supplied brands.
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