Sika Waterbar
Extruded PVC waterstop that seals construction and expansion joints from inside the concrete section, keeping water out of basements, tanks and tunnels.
What is it?
A flexible, plasticised PVC profile cast into the joints of concrete to form a continuous internal barrier against water passing through the section.
Where is it used?
Construction and movement joints in water-retaining and water-excluding structures such as basements, tanks, tunnels and pools.
Why use it?
It gives a permanent mechanical seal that does not depend on surface coatings, and keeps working under hydrostatic pressure for the life of the structure.
How is it applied?
The strip is positioned across the joint, tied to the reinforcement so half its width stays in each pour, and cast integrally into the concrete.
About Sika Waterbar
Sika Waterbar is a family of extruded plasticised PVC waterstops used to seal the joints that are unavoidable in cast-in-situ concrete. Wherever one pour meets the next, or wherever a structure has to be allowed to move, there is a plane through which water can travel. A waterstop is embedded across that plane so that half its width sits in the first pour and half in the second, leaving a continuous flexible diaphragm locked inside the concrete. Water trying to migrate along the joint is forced to follow the long, ribbed path of the profile rather than a straight line, and the ribs also key the strip firmly into the surrounding concrete so it cannot be pushed out under pressure.
For engineers and contractors in India, the appeal of Sika Waterbar is that the seal is built into the structure rather than applied to its face. Membranes and coatings can be damaged during backfilling or lost to abrasion and ageing; a cast-in waterstop is protected inside the concrete section from day one. The range covers both construction joints, where movement is negligible, and expansion joints, where a central bulb lets the two halves of the structure move apart and back without tearing the seal. It is the reason basements, underground tanks, sewage works and tunnel linings can be built in stages and still behave as a single watertight box.
The technical insight
The performance of a PVC waterstop comes down to two things working together: an extended sealing path and mechanical anchorage. The moulded ribs on each wing multiply the distance water must travel to cross the joint, and because that path is long and tortuous rather than direct, the pressure gradient driving the water is spread out and the flow effectively stalls. Those same ribs are gripped by the concrete on both sides, so the strip is anchored against the hydrostatic head trying to blow it out of the joint. On expansion profiles a hollow centre bulb sits directly over the joint gap; as the structure opens and closes, the bulb flexes and takes up the movement while the wings stay locked in the concrete, so the seal accommodates joint travel without straining the anchorage. The plasticised PVC compound is formulated to stay flexible across a wide service-temperature band, which is what lets the material keep sealing decade after decade instead of hardening and cracking.
Where it is used
- Construction joints in basement rafts and retaining walls
- Expansion and movement joints in water-retaining structures
- Underground and elevated water storage tanks and reservoirs
- Sewage and effluent treatment plant structures
- Road, rail and metro tunnel linings and cut-and-cover boxes
- Swimming pool shells and water features
- Bridge abutments, piers and box structures
- Podium slabs, lift pits and other below-grade concrete
Key advantages
- Seal is cast inside the concrete, so it is protected from backfill damage and ageing
- Continuous ribbed profile creates a long, tortuous path that resists water under head
- Expansion profiles with a centre bulb absorb structural movement without tearing
- Plasticised PVC stays flexible across a wide service-temperature range
- Profiles and welded corner/junction fittings give an unbroken run around the structure
- Works independently of surface membranes, adding a second line of defence
- Range of widths lets the profile be matched to wall thickness and water head
- Proven, well-understood technology that consultants readily approve
Limitations & considerations
- Must be positioned and cast integrally with the concrete — it cannot be added to a joint after the pour
- Site joints in the profile must be heat-welded correctly; poor welds are a common leak source
- Displacement or folding during concrete vibration will compromise the seal
- The correct profile type (construction vs expansion) and width must be selected for the joint and water head
- Does not waterproof the concrete face itself — cracking or honeycombing away from the joint needs separate treatment
Selection & best practice
Choose the profile to suit the joint: a flat, ribbed section for construction joints with little movement, and a centre-bulb section for expansion joints that have to move. Position the waterstop so its centreline sits exactly on the joint, with half the width in each pour, and support it clear of the shutter using bar chairs or clips. Tie it to the reinforcement at roughly 300 mm centres with binding wire so it cannot shift or fold when concrete is placed and vibrated. Form all corners, tees and junctions with factory or heat-welded fittings rather than site-butted cuts, and inspect every weld for a continuous molten bead before casting. During concreting, work the concrete carefully around and beneath the profile to avoid trapping voids that would create a leakage path.
Specifications
| Material | Plasticised polyvinyl chloride (PVC-P), UV and chemical resistant |
| Profile types | Flat/ribbed (construction joints) and centre-bulb (expansion joints) |
| Available widths | 150, 200, 230, 240 and 300 mm |
| Tensile strength | ≥ 10 N/mm² (DIN 53504) |
| Elongation at break | ≥ 380% (DIN 53504) |
| Shore A hardness | 62 ± 5 (DIN 53505) |
| Tear strength | ≥ 8 N/mm² (DIN 53507) |
| Reference standard | DIN 7865 (PVC waterstops for joints in concrete) |
| Installation | Cast integrally into the joint; heat-welded corner and junction fittings |
Industry use cases
Basements & Below-Grade
Cast-in across raft and wall construction joints so a staged basement pour behaves as one watertight box against groundwater.
Water & Wastewater
Seals joints in reservoirs, clear-water tanks and sewage treatment structures where leakage is not acceptable in either direction.
Tunnels & Metro
Runs through construction and movement joints of cut-and-cover boxes and tunnel linings to keep the structure dry under head.
Pools & Water Features
Provides a permanent internal seal at joints in swimming pool shells and architectural water bodies.
Bridges & Infrastructure
Waterproofs joints in abutments, piers and box structures exposed to standing or percolating water.
Frequently asked questions
What is the difference between the flat and centre-bulb Sika Waterbar profiles?
Which width should I specify?
Can a waterstop be fitted after the concrete is poured?
How are corners and junctions handled?
Does the waterstop make the whole concrete watertight?
Does Space Arc supply Sika Waterbar across India?
How we position Sika Waterbar
Sika Waterbar sits in Sika’s joint-sealing line-up alongside Sika swellable waterstops and SikaSwell profiles for tight or congested joints, and Sikadur and Sikaflex sealants for the surface side of movement joints; for whole-structure watertightness it pairs naturally with Sika waterproofing admixtures and Sikalastic membranes. Where a project is standardised on Fosroc, the equivalent cast-in PVC waterstop is the Supercast PVC range, and complementary Fosroc systems such as Nitobond, Renderoc and Conbextra can complete the joint and repair scope. Space Arc supplies both families and can match the waterstop to whatever the rest of the specification calls for.
Fosroc Supercast PVC Waterstop — A specifier standardised on Fosroc, or needing Fosroc’s fully-continuous multi-bulb profiles and brass-eyelet fixing, would choose the Supercast PVC range as the direct cast-in equivalent.
Related Sealants & Joint Treatment products
Source Sika Waterbar for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.