PVC Waterstops — Dseal Profiles For Watertight Concrete Joints
Ribbed centre-bulb, dumbbell and kicker-type PVC waterstops from our own Dseal line, plus the Fosroc Supercast range and hydrophilic swelling bars — the primary seal for every construction and expansion joint that must hold water.
The Seal You Cast In, Not Stick On.
A waterstop is a flexible, impermeable strip embedded across a concrete joint — the primary seal against water under pressure.
Concrete joints move: temperature fluctuations, settlement and loading stresses all work on them, and any coating applied later works from the wrong side. A correctly placed waterstop bridges the joint from inside the pour, accommodating movement while blocking water. Dseal waterstops are extruded from high-grade plasticized PVC — durable, flexible, corrosion-immune, easily heat-welded and resistant to acids, alkalis, salts, chlorinated water, seawater and diesel oil.
Alongside our own profiles we supply the Fosroc Supercast PVC range — internal and external profiles with factory-made intersections — and hydrophilic swelling types for construction joints.
Which Type Goes In Which Joint.
| Profile | Placement | Best suited for |
|---|---|---|
| Ribbed centre-bulb | Embedded, centrally in joint | Multipurpose — ribs give a firm mechanical grip in concrete; areas with differential settlement; construction and expansion joints |
| Dumbbell | Embedded, central bulb aligned with joint | Sites with significant temperature variation — the bulb accommodates expansion and contraction |
| Kicker type (external) | External face of joint | Rafts and kickers where embedded types cannot be used due to interference with steel reinforcement |
| Replaceable type | Specialized detail | A serviceable design developed by the Ganga Modernisation Authority, Roorkee — where the seal must be renewable |
| Hydrophilic swelling bar | Surface-fixed on construction joint | Construction joints and pipe penetrations where a cast-in PVC profile is impractical — swells on contact with water |
Sizing & Site Jointing.
Three sizing rules keep a waterstop out of trouble:
- Width should not exceed the thickness of the concrete section
- Width should be at least six times the largest aggregate size
- Thickness is chosen against the expected hydrostatic pressure
On site, lengths are joined by heat welding: trim the ends square with a knife, heat the electric welding blade, press both ends against it until molten, withdraw the blade upward, then join the molten ends and hold firmly for 20–30 seconds. Inspect every weld — intersections are a known weak point, which is why we recommend factory-made junction pieces wherever the layout allows.
Secure the waterstop to the reinforcement with wire ties, hog rings or clamps so it cannot fold or displace during the pour, and vibrate the concrete properly around it.
Wherever Concrete Must Hold Or Exclude Water.
Water-retaining structures: sewage and water treatment plants, tanks and reservoirs, swimming pools, dams, canals and aqueducts. Water-excluding structures: basements, underground car parks, tunnels, retaining walls and bridge abutments.
Frequently Asked.
Which waterstop type do I need — construction joint or expansion joint?
For expansion joints with real movement, use a centre-bulb profile — dumbbell or ribbed centre-bulb — with the bulb aligned to the joint gap. For construction joints, a ribbed profile or a hydrophilic swelling bar is usually sufficient. Where reinforcement congestion prevents embedding, use an externally placed kicker type.
How do I size a PVC waterstop?
Keep the width no greater than the concrete section thickness and at least six times the largest aggregate size; pick thickness against the expected hydrostatic pressure. Share your section drawing on WhatsApp and we will confirm the profile and width.
Why do waterstops fail?
About 75% of failures come from misallocation — the wrong product for the joint — and poor consolidation or compaction leaving voids and honeycombs around the profile. The rest are mostly weld failures at intersections and structural over-stressing of the PVC. All four are preventable with correct selection, secure fixing and proper vibration.
How are PVC waterstops joined on site?
By heat welding with an electric blade: square the ends, melt both against the heated blade, join the molten faces and hold firmly for 20–30 seconds, then inspect the weld. Use same-width, same-design lengths only, and factory-made intersections for T- and X-junctions where possible.