Why modifier type matters
Torch-applied bitumen membranes are not interchangeable rolls of asphalt. The polymer modifier—APP (atactic polypropylene) or SBS (styrene-butadiene-styrene)—changes how the sheet behaves under sun load, thermal movement, and detailing stress. Petroseal Enterprises manufactures both lines in Lahore under the PetroGrip brand, so contractors and consultants can match chemistry to exposure rather than defaulting to one product nationwide.
APP is typically the exposed-roof cap sheet because of higher softening point and UV stability. SBS is specified where flexibility, lap integrity after movement, and crack-bridging matter—basements, split slabs, podiums with planters, and walls with structural joints. Choosing correctly at tender stage avoids costly tear-offs when a rigid cap sheet cracks at a movement joint or when a flexible ply is left fully exposed without the right surfacing.
Modifier chemistry is a design decision—not a warehouse decision.
— Petroseal specification desk
PetroGrip APP: heat resistance and exposed roofs
PetroGrip APP torch applied membrane is formulated for high softening point and excellent stability under direct solar exposure. On fully exposed flat roofs, APP is typically the cap sheet in 3mm or 4mm, welded at laps with a propane torch on a primed concrete or metal deck.
APP is available from Petroseal in 2mm, 2.5mm, 3mm, and 4mm thicknesses. Plain APP is common in protected layers—below screed, under tiles, or as a base ply—while the top exposed ply carries aluminum or granular surfacing.
PetroGrip SBS: flexibility for movement-prone structures
PetroGrip SBS torch applied membrane offers superior flexibility and elongation compared to APP. SBS sheets accommodate thermal expansion of large podium slabs, subtle structural settlement, and cyclic movement at wall-to-slab junctions. For basement walls, retaining structures, and split slabs with occupied space below, SBS 3mm or 4mm is frequently the primary waterproofing ply.
SBS is not a substitute for correct surfacing on exposed roofs. Where SBS is used at grade or on a roof, plain, aluminum, and granular finish options still apply—the design intent must be clear: flexible ply at movement zones, with traffic and UV handled by surfacing and protection layers.
Quick comparison: APP vs SBS
| Criterion | PetroGrip APP | PetroGrip SBS |
|---|---|---|
| Primary strength | Heat & UV stability on exposed roofs | Flexibility & crack bridging |
| Common thickness | 2mm–4mm (4mm cap on exposed decks) | 3mm–4mm below grade & podiums |
| Typical exposure | Exposed cap sheet, industrial roofs | Basements, rafts, split slabs, podiums |
| Surfacing | Plain, aluminum, granular | Plain, aluminum, granular |
| Manufacturing | Petroseal Enterprises, Lahore | Petroseal Enterprises, Lahore |
Plain, aluminum, and granular surfacing
Surfacing is separate from modifier type but equally critical. Plain finish membranes are used where the sheet is protected—buried in fill, under screed, or covered by insulation and another ply. Plain APP or plain SBS on an unprotected roof deck will not deliver the service life owners expect.
Aluminum-faced sheets provide a reflective cap layer for exposed roofs subject to direct sun. Granular surfacing adds mineral protection for traffic-related areas and maintenance zones without a full paver system.
Specification checklist
- Document whether each ply is APP or SBS, thickness, surfacing, primer type, and overlap width at laps and T-junctions.
- Require torch-applied membranes only on dry substrates within the temperature window on the datasheet.
- Inspect welds by probing side laps and end laps before covering.
- For split slabs and podium planters, show SBS at the structural waterproofing line and APP only where the exposure schedule calls for a heat-stable cap.
PetroGrip APP and SBS are manufactured in Pakistan by Petroseal Enterprises—not imported commodity rolls with inconsistent modifier content. Request side-by-side datasheets when your bill of quantities still lists generic torch membrane without a modifier call.