Basement leakage and construction sequence

Basements fail when waterproofing is applied to green concrete, left unprotected against backfill, or stopped short of the raft-to-wall junction. High water tables and monsoon recharge create hydrostatic pressure on raft slabs and retaining walls. A bitumen membrane system must be continuous, flexible at joints, and compatible with the protection layer before fill arrives.

Petroseal manufactures PetroGrip SBS torch applied membrane for movement-prone below-grade structures and PetroSelfGrip for detail zones, lift pits, and flame-restricted areas—both produced in Lahore with traceable batch marking.

Why SBS dominates below-grade torch specs

SBS modified bitumen offers higher flexibility and crack-bridging than APP on basement walls and rafts subject to settlement and thermal movement. PetroGrip SBS torch membrane is supplied in 3mm and 4mm with plain, aluminum, or granular surfacing depending on whether the ply is buried or temporarily exposed.

Never backfill against an unprotected membrane—puncture from aggregate is one of the most common basement leak causes on Pakistani sites.

The membrane is only as good as the protection course and the inspection hold before backfill.

PetroSelfGrip at details and congested zones

Lift pits, sumps, pipe bundles, and internal coring zones often prohibit open flame. PetroSelfGrip in 1.5mm or 2mm bonds cold to primed concrete for patches and transitions. Lap self-adhesive to torch membrane with the overlap width and primer type shown on the project detail.

Bathroom pods over basement parking may use PetroSelfGrip on the pod slab while SBS torch covers the structural raft—one brand, two methods, documented in the method statement.

Protection, drainage, and testing

  • Specify protection board or screed before sharp backfill
  • Show horizontal drainage or relief where hydrostatic pressure is high
  • Photograph primer, laps, upturn heights before protection
  • Flood test raft and blind-side walls where accessible

Coordination with DPC and superstructure

Basement waterproofing must tie into PetroDPC at plinth level to stop rising damp in masonry above grade. Podium decks above parking often transition from SBS below to APP cap sheets above with Green Insulation XPS or PUF. Draw vertical continuity from raft through wall, podium, and main roof.

PVC waterstops at construction joints complement membrane lines where structural drawings call for embedded profiles during pour.

Specification support from Petroseal

Send raft area, wall height, water table notes, and backfill type for a PetroGrip build-up recommendation. Early involvement catches waterstop placement and reglet heights before rebar congestion makes fixes expensive. Contact 0321 8489737 or petrosealenterprises.com for basement submittals manufactured in Lahore.