Fosroc Supercast PVC Waterstop
A flexible PVC water barrier cast into concrete joints, stopping water at the very plane where two pours meet in basements, tanks and treatment works.
What is it?
An extruded polyvinyl chloride (PVC) strip embedded across a concrete joint so that water cannot travel along the interface between two pours or through a moving joint.
Where is it used?
Construction and expansion joints in basements, rafts, water tanks, STPs, ETPs, reservoirs, swimming pools, tunnels and other liquid-retaining or below-ground structures.
Why use it?
It builds waterproofing into the structure itself rather than relying only on a surface coating, giving a permanent, movement-tolerant seal at the most vulnerable point of any water-retaining pour.
How is it applied?
The profile is positioned centrally on the joint line, tied to the reinforcement, and cast into the concrete; lengths are heat-welded on site and corners handled with factory junctions.
About Fosroc Supercast PVC Waterstop
Every water-retaining or below-ground concrete structure is poured in stages, and every place where fresh concrete meets an earlier pour, or where the structure is designed to move, is a potential leak path. Fosroc Supercast PVC Waterstop addresses that path directly. It is a flexible strip extruded from a high-grade PVC compound and cast into the joint so that it sits astride the interface, forcing any water that tries to migrate through the joint to follow a long, tortuous route around the ribs and bulbs of the section rather than a straight line through the concrete. Because the barrier is inside the section, it keeps working for the life of the structure without depending on access to the face.
For engineers and contractors across Delhi NCR and the rest of India, the appeal is that one product family covers both kinds of joint. Flat and ribbed profiles suit rigid construction joints, where the two pours are not expected to move relative to each other; centre-bulb profiles carry a hollow bulb over the joint line that opens and closes as an expansion or movement joint breathes, so the waterstop stretches instead of tearing. Space Arc Engineering supplies the Supercast PVC range as an authorised Fosroc distributor and applicator, and pairs it with the welding tools, factory junctions and complementary products needed to detail a joint properly on site.
The technical insight
The waterstop works on two principles at once. The first is the tortuous path: by casting a wide, ribbed strip across the joint, the distance water must travel to get from the wet face to the dry face is greatly extended, and the ribs key mechanically into the concrete so water cannot simply slip along the PVC-to-concrete contact. The second, in centre-bulb profiles, is accommodation of movement. The hollow bulb sits exactly on the joint line, so when the joint opens under thermal or structural movement the bulb unrolls and the flexible PVC elongates rather than the seal splitting. The compound is formulated for durability in this role, with a Shore A hardness of about 76 and elongation at break well over 300 percent, so it stays flexible and recovers after repeated cycles. On site the continuity of that barrier matters as much as the material: butt joints in straight runs are made by heat-welding cut ends together so the section fuses into one continuous piece, and changes of direction use purpose-made factory-welded L- and T-junctions, avoiding the weak, hand-cut corners that are the usual cause of waterstop failure.
Where it is used
- Construction joints in basement retaining walls and raft foundation slabs
- Expansion and movement joints in water-retaining reservoirs and storage tanks
- Sewage treatment plant (STP) and effluent treatment plant (ETP) concrete structures
- Below-ground and tunnel joints requiring long-term hydrostatic sealing
- Water treatment plant basins, clarifiers and filter beds
- Swimming pool shells and balancing tanks
- Podium, terrace and planter box joints on structural slabs
- Culverts, channels and other cast in-situ hydraulic structures
Key advantages
- Seals the joint from within the concrete, independent of any surface coating
- One range covers both rigid construction joints (flat/ribbed) and moving joints (centre-bulb)
- Ribbed profile lengthens the water percolation path and keys into the concrete
- Centre-bulb accommodates joint movement without tearing the seal
- High elongation and flexible PVC compound recover after repeated movement cycles
- Continuous barrier achieved by heat-welding on site, with factory L- and T-junctions for corners
- Suitable for potable-water contact where the WRc-approved grade is specified
- Backed in India by Fosroc technical support and Space Arc applicator services
Limitations & considerations
- It is an internal system that must be cast into concrete during pouring, so it cannot be retrofitted into a joint after the pour has set
- Performance depends heavily on correct central positioning and firm tying to the reinforcement; a displaced or floating waterstop leaks
- Site butt joints and corners must be properly heat-welded, which needs the correct welding tool and a trained operator
- It seals the joint plane only and is not a substitute for full-structure waterproofing where an integral admixture or membrane is also required
- PVC can be damaged by careless vibration, over-poking or foot traffic during concreting, so it needs protection until the pour is complete
Selection & best practice
Select the profile to match the joint: flat or ribbed for construction joints, and a centre-bulb section sized to the expected movement for expansion joints. Set the waterstop out so it is centred exactly on the joint line, with half its width in each pour, and tie it securely to the reinforcement or support it on chairs so it cannot sag, roll or float when concrete is placed. For vertical wall joints, wire the strip to the rebar; for horizontal slab joints, support it on the transverse steel. Make straight-run joints by cutting the ends square and heat-welding them with the purpose-made Fosroc welding tool until a continuous bead forms, and use factory-welded junctions at all corners and intersections rather than site-cut mitres. Compact the concrete carefully around and beneath the section so no voids form against the PVC, and protect the exposed leg from damage until the second pour is cast. Where the structure will hold potable water, confirm the WRc-approved grade is specified.
Specifications
| Material | Extruded high-grade polyvinyl chloride (PVC) compound |
| Profile types | Flat and ribbed (construction joints); centre-bulb (expansion / movement joints); surface and centrally-placed sections |
| Typical widths | 150 mm, 200 mm, 230 mm and 300 mm (standard range; other widths per profile) |
| Hardness | Approx. Shore A 76 (±3) |
| Tensile strength | ≥ 16 MPa (ASTM D638) / approx. 14 N/mm² to BS 2782 |
| Elongation at break | ≥ 320% (typical, ASTM D638) |
| Specific gravity | Approx. 1.32 (±0.02) |
| Standard | Complies with BS 2571 (Class 3, Type E3); potable-water grade holds WRc approval |
| Jointing | On-site heat-welded butt joints; factory-welded L- and T-junctions for corners |
Industry use cases
Water & Wastewater Infrastructure
Reservoirs, STP/ETP tanks, clarifiers and filter beds rely on centre-bulb and ribbed waterstops to seal every construction and movement joint against continuous hydrostatic head.
Basements & Below-Ground Structures
Raft slabs and retaining walls in commercial and residential basements use flat/ribbed profiles at kicker and construction joints to keep the box watertight from within.
Metro, Tunnels & Underground
Cut-and-cover boxes, tunnels and underground service structures use PVC waterstops to seal segmental construction joints under groundwater pressure.
Swimming Pools & Water Features
Pool shells, balancing tanks and decorative water bodies use waterstops at wall-to-floor and expansion joints to prevent seepage into surrounding structure.
Industrial & Effluent Containment
Bunds, channels, culverts and industrial containment slabs use ribbed profiles to seal joints exposed to standing liquids and process water.
Frequently asked questions
What is the difference between the flat/ribbed and centre-bulb profiles?
Can Supercast PVC Waterstop be installed after the concrete is poured?
How are lengths of waterstop joined on site?
Which width should I specify?
Is it safe for potable (drinking) water tanks?
Do I still need other waterproofing if I use a waterstop?
How we position Fosroc Supercast PVC Waterstop
Supercast PVC Waterstop is the cast-in joint barrier at the core of a water-retaining detail, and it works best as part of a system rather than alone. Within the Fosroc family, pair it with Supercast SW, the hydrophilic swelling strip that bonds to an already-cast or heavily-reinforced joint face where a dumbbell waterstop cannot be installed, and reach for a crystalline or integral admixture such as the Conplast or Auracast range to densify the surrounding concrete. For non-moving cracks and tie-bolt holes around the same pour, Fosroc’s cementitious and epoxy grouts complete the watertight box. Where a project standard calls for a different brand, Space Arc also supplies equivalent PVC waterstops and hydrophilic strips from Sika and Dr. Fixit, so the specifier can match an approved vendor list without compromising the joint detail.
Related Sealants & Joint Treatment products
Source Fosroc Supercast PVC Waterstop for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.