Technical document
Method Statement: Double-Layer SBS Basement Waterproofing
Method statement PS-MS-02: positive-side two-ply PetroGrip SBS basement waterproofing on raft and walls, with PVC waterstops at joints.
This method statement covers positive-side basement waterproofing using two plies of PetroGrip SBS torch-applied membrane under the raft and on external retaining walls, continuous through the raft-to-wall junction, with PVC waterstops as a second line of defence at construction joints.
It includes dewatering conditions, pile-head details, waterstop fixing and welding, protection and backfilling sequence, and the hold points to sign before each cover-up.
Key specifications
Values shown are taken from the published brochure/TDS. Project acceptance follows the approved batch certificate and consultant specification.
- Document
- PS-MS-02, 4 pages
- System
- PetroGrip SBS, two plies, positive-side
- Laps
- Side 100 mm / end 150 mm; plies offset by half a roll width
- Raft tails
- Both plies project at least 300 mm for lapping to wall membrane
- Wall membrane
- Carried at least 150 mm above finished ground level
- Protection
- 50 mm screed on raft; protection board on walls before backfill
Applications
- — Basements under groundwater or hydrostatic pressure
- — Raft foundations and external retaining walls
- — Below-grade structures needing redundant protection
Related products
- PetroGrip SBS
SBS-modified torch membrane—3mm and 4mm with plain, aluminum, or granular surfacing.
- PVC Waterstoppers
PVC water-stops for watertight concrete construction joints.