Fosroc Proofex Torchseal 3P & 4P
Torch-applied APP-modified bitumen membranes with a 180 g/m² non-woven polyester core for basements, podiums, roofs and tanking in aggressive ground conditions.
What is it?
A pair of prefabricated, torch-applied waterproofing membranes (3mm Proofex Torchseal 3P and 4mm 4P) made from APP-modified bitumen reinforced with a 180 g/m² non-woven polyester core.
Where is it used?
Basements and raft foundations, podium and car-park decks, roof slabs, retaining structures, tunnels and subways, and tanking where aggressive groundwater is present.
Why use it?
It delivers a fully-bonded, joint-overlapped monolithic barrier with high puncture resistance and reliable performance under hydrostatic and ground-water loading on Indian infrastructure and building projects.
How is it applied?
Float-finished concrete is primed with Torchseal Primer, then the membrane is unrolled, flame-bonded with a propane torch with 100mm side and 150mm end overlaps, and protected before backfilling or screeding.
About Fosroc Proofex Torchseal 3P & 4P
Fosroc Proofex Torchseal 3P and 4P are factory-produced, torch-applied bituminous waterproofing membranes engineered for structural and below-grade waterproofing. Both grades are manufactured from premium-grade, heavily APP (atactic polypropylene) modified bitumen and carry a central reinforcing core of rot-proof non-woven polyester fabric weighing 180 g/m². The only difference between the two is gauge: Proofex Torchseal 3P is 3mm thick (nominal ~3.5 kg/m²) and 4P is 4mm thick (nominal ~4.5 kg/m²). The thicker 4P grade is typically specified where mechanical demand, water head or service life expectations are higher, such as deep basements and podium decks, while 3P suits roofs, shallow tanking and damp-proofing duties.
The polyester carrier is what separates these membranes from cheaper glass-fleece or unreinforced felts. It gives the sheet its dimensional stability, high elongation and excellent resistance to piercing and ground-stress, so the membrane bridges shrinkage cracks and tolerates the rough handling typical of Indian sites. Because the binder is APP-modified rather than SBS-modified, the membranes have a high softening point (around 150 deg C to ASTM D36) and good heat and UV tolerance, which matters under Delhi NCR and pan-India summer roof temperatures. The membranes are supplied in 10 m x 1 m rolls in plain, mineral-slated and aluminium-faced surface finishes, with double-reinforced variants available on request.
For Space Arc Engineering’s contractor and consultant clients, Proofex Torchseal 3P/4P represent the workhorse “torch membrane” tier of the Fosroc waterproofing portfolio: a proven, code-familiar, BBA-lineage system that site teams and waterproofing applicators across India already know how to install, inspect and warrant.
The technical insight
The performance logic of Proofex Torchseal 3P/4P rests on the pairing of an APP-modified bitumen compound with a non-woven polyester core. APP modification raises the bitumen’s softening point to roughly 150 deg C (ASTM D36), so the membrane resists flow and slumping on hot, sun-exposed Indian roofs far better than oxidised or lightly-modified felts. The trade-off is cold-temperature behaviour: low-temperature flexibility is around -5 deg C (DIN 52123), which is comfortable for almost all Indian climates but means the membrane should not be torched or sharply folded in genuinely sub-zero conditions without warming. The 180 g/m² spunbond polyester carrier delivers the measured tensile strength of approximately 790 N/5cm longitudinal and 730 N/5cm transverse with elongation of about 65 percent and 69 percent respectively (UEAtc method), giving the sheet the crack-bridging and puncture resistance that thin bituminous coatings cannot match. Torch-bonding melts the underside compound directly onto a primed substrate, producing a fully-adhered membrane (not a loose-laid one), which limits lateral water tracking if the sheet is later punctured, an important serviceability advantage in basements. The thicker 4P grade simply carries more compound over the same core, improving puncture margin and effective service life under permanent hydrostatic head.
Where it is used
- Basement raft slabs, retaining walls and below-ground tanking, including sites with aggressive or sulphate-bearing groundwater
- Podium decks, car-park decks and terrace/roof slabs requiring trafficable or buried protected waterproofing
- Tunnels, subways, underpasses and other civil and infrastructure works
- Water-retaining and water-excluding concrete structures
- Damp-proof membrane (DPM) layers beneath screeds and finishes
- Protection waterproofing over piled foundations and ground beams ahead of backfilling
Key advantages
- High-strength 180 g/m² polyester core gives excellent puncture and tear resistance plus good crack-bridging elongation (~65-69%)
- Fully torch-bonded to the substrate, reducing lateral water migration compared with loose-laid systems
- High softening point (~150 deg C) resists flow and bubbling on hot Indian roof and deck surfaces
- Chemically resistant binder suited to tanking in aggressive groundwater conditions
- Factory-controlled, consistent thickness (3mm or 4mm) versus variable site-applied liquid coatings
- Familiar, widely-installed system with an established applicator base and Fosroc on-site technical support across India
- Readily formed to contours and detailed around upstands, pipe penetrations and corners
- Available in plain, mineral-slated and aluminium-faced finishes for exposed or protected use
Limitations & considerations
- Requires skilled torch application with an open propane flame; quality and fire safety depend heavily on the applicator
- Open-flame work is restricted or prohibited near combustible substrates, insulation, gas lines and in confined/occupied spaces
- Low-temperature flexibility limited to about -5 deg C; not ideal for genuinely sub-zero installation without warming
- Substrate must be float-finished, dry, frost-free and properly primed with Torchseal Primer; re-priming needed if left over 24 hours
- Lapped-sheet system means watertightness is only as good as the side (100mm) and end (150mm) overlaps and detailing
- Needs a protection layer/screed before backfilling or trafficking; the membrane is not a finished wearing surface
- Bituminous membranes are heavier and less suited to highly complex geometries than liquid-applied systems
- Shelf life 12 months; rolls must be stored upright/horizontal as specified, below 30 deg C, away from heat and sunlight
Selection & best practice
Specify 4P (4mm) for permanently water-loaded duties such as deep basements and podium decks, and 3P (3mm) for roofs, shallow tanking and DPM use. Always float-finish the concrete, remove laitance and nibs, ensure the surface is dry and frost-free, then apply Torchseal Primer and let it become tack-free before torching; re-prime any area left exposed beyond 24 hours. Maintain a minimum 100mm side overlap and 150mm end overlap, stagger end laps, and fully seal all laps so a continuous bead of bitumen is visible. Reinforce all internal/external corners, upstands, construction joints and pipe penetrations with additional membrane collars. Heat the membrane to melt the underside compound without scorching the polyester core, and roll firmly to expel air. Enforce hot-work permits, keep extinguishers at hand and avoid open flame near combustibles or insulation. Protect the completed membrane promptly with a protection board or screed before backfilling or trafficking, and never leave it exposed to UV longer than necessary unless an aluminium-faced grade is used.
Specifications
| Product type | Torch-applied APP-modified bitumen waterproofing membrane |
| Reinforcement core | Non-woven polyester fabric, 180 g/m² (rot-proof) |
| Thickness (3P / 4P) | 3 mm / 4 mm |
| Nominal weight (3P / 4P) | ~3.5 kg/m² / ~4.5 kg/m² |
| Softening point | ~150 deg C (ASTM D36) |
| Penetration | 17-25 dmm (ASTM D5) |
| Tensile strength (long. / trans.) | ~790 N/5cm / ~730 N/5cm (UEAtc) |
| Elongation at break (long. / trans.) | ~65% / ~69% (UEAtc) |
| Flexibility at low temperature | -5 deg C (DIN 52123) |
| Surface finishes | Plain, mineral-slated, aluminium-faced; double-reinforced on request |
| Roll size | 10 m long x 1 m wide |
| Recommended primer | Fosroc Torchseal Primer (coverage 0.2-0.8 lt/m²) |
| Overlaps | 100 mm side, 150 mm end (minimum) |
| Shelf life / storage | 12 months; cool dry store below 30 deg C, out of direct sunlight |
Industry use cases
Commercial & residential basements
Multi-level basement rafts and retaining walls in Delhi NCR high-rises tanked with 4P beneath a protective screed to resist fluctuating water tables and aggressive soils.
Infrastructure & transport
Metro subways, vehicular underpasses and tunnel sections where a robust, puncture-resistant torch membrane is needed over structural concrete.
Podium & car-park decks
Buried, protected waterproofing to landscaped podiums and parking decks where traffic and planter loads demand the 4mm 4P grade.
Roofs & terraces
Concrete roof slabs and terraces waterproofed with 3P, often in aluminium-faced finish for exposed reflective performance against summer heat.
Water & civil structures
Retaining structures, ground beams and water-excluding works requiring a fully-bonded, chemically-resistant barrier ahead of backfilling.
Frequently asked questions
What is the difference between Proofex Torchseal 3P and 4P?
Is Proofex Torchseal 3P/4P suitable for basements with high water tables?
What primer is used and is it mandatory?
How is the membrane installed and what overlaps are required?
How does it compare with liquid-applied waterproofing membranes?
What is the shelf life and how should rolls be stored?
How we position Fosroc Proofex Torchseal 3P & 4P
Within the Fosroc range, Proofex Torchseal 3P/4P sit as the standard polyester-reinforced torch-membrane tier, sharing a family with the slated/aluminium 3S-4S-5S grades and the polyester 3PI/4PI variants; for complex detailing or seamless coverage Space Arc typically pairs them with liquid systems such as Fosroc Brushbond (cementitious) or Proofex/PU membranes, and uses Torchseal Primer plus Proofex protection boards as accessories. Against the wider market, these compete directly with torch-applied APP/SBS membranes from STP (Cosmofin/torch felts), Sika (SikaBit / Sarnafil bituminous lines), Dr. Fixit (Torchshield) and other MBS-type membranes. Honestly assessed, Proofex Torchseal is a mature, mid-premium APP membrane: strong on heat tolerance and a familiar installed base, but like all torch systems it depends on applicator skill and open-flame safety, and SBS-modified or self-adhesive alternatives may be preferred for colder climates or fire-restricted locations. As an authorised Fosroc distributor for Delhi NCR and pan-India, Space Arc Engineering supplies genuine stock with batch traceability and can advise on grade selection, primer, protection and compatible Fosroc detailing products.
Related Waterproofing products
Source Fosroc Proofex Torchseal 3P & 4P for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.