Direct answer
A construction joint is where today’s pour meets yesterday’s hardened concrete—no designed expansion gap. An expansion joint deliberately separates elements to move. Waterproofing must follow that distinction: rigid waterstop and membrane continuity for construction joints; movement-capable systems for expansion joints.
Petroseal supplies PVC waterstops for construction joints on basements, tanks, and rafts, integrated with PetroGrip SBS membrane lines. Expansion joints need additional joint fillers, reglets, and sometimes metal profiles per structural spec—never only a bead of sealant.
Comparison
| Joint type | Movement | Waterproofing approach |
|---|---|---|
| Construction joint | Minimal | Cast-in PVC waterstop + membrane upturn both sides |
| Expansion joint | Designed cyclic | Compressible filler, joint profile, flexible membrane system |
| Cold joint (poor practice) | Unplanned | Repair concrete + treat as construction joint after approval |
Installation coordination
Waterstops are placed before concrete pour—site errors cannot be fixed by external torch membrane alone if the stop is missing. Align Petroseal waterstop centres with structural drawings; photograph before pour. Lahore contractors rushing pour schedules skip this step more often than membrane brand choice causes failures.