Direct answer
Basement system selection starts with groundwater behaviour and whether you can waterproof the outside face before backfill. With positive-side access and moderate risk, a designed PetroGrip SBS assembly—primer, 4mm primary ply, laps, upturns, protection board—may suffice. With high hydrostatic pressure or zero tolerance for leakage, specify double-layer SBS, embedded PVC waterstops at construction joints, and coordinated raft-to-wall details.
If the basement already leaks and external access is blocked, stop and diagnose before choosing negative-side cementitious or injection options. Petroseal publishes the positive-side path as default for new Pakistani commercial and residential basements.
Selection matrix
| Site signal | Recommended direction | Petroseal anchor page |
|---|---|---|
| Low persistent head, good drainage | Single-ply SBS external + protection | /systems/sbs-waterproofing |
| High head, critical use | Double-layer SBS + waterstops | /systems/double-layer-sbs-basement |
| Congested details, no torch | PetroSelfGrip patches + SBS field sheets | /products/self-adhesive-bitumen-membrane |
| Existing leak, no external access | Diagnosis-led remediation | /waterproofing/basement + cementitious system |
| Raft + retaining wall junction | Continuous horizontal + vertical build-up | /blog/raft-to-retaining-wall-waterproofing-detail |
Substrate and sequence
Concrete must meet minimum cure and moisture limits before torch work. Green concrete, form-release incompatibility, and cold joints without waterstop are failure drivers unrelated to brand. Petroseal method statements (where published on downloads) define primer type and lap width—apply the same discipline whether rolls are PetroGrip or another manufacturer’s submittal.
Sequence coordination: waterproofing before backfill, protection before sharp aggregate, and MEP penetrations sleeved per drawing—not cored after backfill without detail review.
Joints, penetrations, and raft transition
Construction joints require waterstop profiles cast into the concrete plus compatible membrane turn-ups. Expansion joints need different treatment—see the construction vs expansion joint guide. Raft-to-wall is the highest leak frequency detail; draw membrane continuity from horizontal raft ply up the wall reglet without a gap at the fillet.
PVC waterstoppers from Petroseal complement SBS lines on many Pakistani consultant drawings.
Documentation for consultants
- Link /waterproofing/basement in the specification preamble
- Name APP vs SBS per ply—never generic torch membrane
- Reference PetroGrip TDS download slugs from /downloads
- Require inspection hold photos before protection
- List comparable Petroseal projects only where scope matches
Market context without substituting engineering
Domestic manufacturers (Petroseal PetroGrip, Roofline, Grace) and importers (Sika, etc.) can all supply rolls that fit a correct system. Petroseal’s advantage on Pakistani basements is combined manufacturing in Lahore, published system build-ups, and indexed project evidence—not unnamed commodity rolls. Choose the system first; then lock the manufacturer on the submittal.