Frequently Asked Questions

What is the correct fixing and support method for Sika Waterbar during concrete casting to prevent displacement and damage by concrete vibration?

Correct Sika Waterbar fixing is critical — the most common waterstop installation failure in Indian basement construction is waterstop displacement or buckling during concrete vibration, creating gaps and voids at the waterstop-concrete interface that become permanent leak points. The correct method depends on whether the waterstop is being installed in a pour-in-place (continuous pour) joint or in a stop-end (construction joint). For pour-in-place installation (vertical joints poured in two lifts): the lower half of the Sika Waterbar width is embedded in the first pour and the upper half projects above the top of the concrete. Support the projecting upper half against buckling during the first pour using steel bar chairs or plastic clips at 300 mm centres along the waterstop length. Tie the Sika Waterbar to the horizontal reinforcement bars using 16-gauge binding wire at maximum 300 mm centres — not to the form face, as this prevents removal. For the second pour, leave the projecting waterstop vertical and cast the second pour against it. For horizontal slab joints: the Sika Waterbar is positioned centrally in the joint (half in the slab and half in the wall kicker) and must be supported on the bottom reinforcement bars. Do NOT allow the Sika Waterbar to rest on the blinding concrete or form face without support — it must be held centrally in the concrete section. At all turns, corners, and T-junctions, use factory-fabricated Sika Waterbar fittings (corners, tees) rather than site-cut and heat-fused joints to ensure a leak-free profile.

How should Sika Waterbar construction joints be waterproofed when the waterstop has been accidently omitted from a poured concrete basement wall panel?

When Sika Waterbar has been accidentally omitted from a basement wall construction joint that is already cast, the primary waterstop system is lost and alternative or remedial waterproofing of the joint becomes necessary. The available options, in decreasing order of waterproofing effectiveness, are: Option 1 — Sika Injectable Hose (SIH) system: if the joint is still accessible (the adjacent panel has not yet been poured), install Sika injectable hose along the full joint length at the time of the adjacent panel pour; the injectable hose can later be injected with polyurethane injection resin if the joint is found to be leaking after waterproofing. Option 2 — Crystalline waterproofing layer: if the joint has been poured and is now accessible only from one face, apply a Sika Crystalline waterproofing treatment (SikaTop 107 Seal or brush-on crystalline slurry) over the full joint width from the accessible face, combined with a sealant bead of Sikaflex or Sika Boom (polyurethane injection foam) in the joint groove. Option 3 — Injection grouting: if the structure is already complete and the joint is leaking, inject with polyurethane hydrophilic injection resin through drill holes from the accessible face to fill the joint void and stop active water ingress. None of these remedial options provides the same long-term reliability as a correctly installed Sika Waterbar embedded at the time of construction — always insist on waterstop installation inspection before approving each concrete pour.

What is the hydrostatic head resistance of 200 mm Sika Waterbar and how does it compare to the groundwater pressure at 6 metre basement depth in Delhi NCR?

Sika Waterbar 200 mm (standard ribbed profile) tested per DIN 7865 provides resistance to hydrostatic water pressure of at least 10 metres of water head — equivalent to 0.1 MPa or approximately 1 bar. At a basement excavation depth of 6 metres below ground level in the Gangetic alluvial plain (Delhi NCR, Ghaziabad, Noida area), the design groundwater pressure at the base slab level depends on the groundwater table elevation. If the groundwater table is at 1 metre below existing ground level (common in low-lying areas of the NCR and flood-plain areas near the Yamuna), the hydrostatic head at 6 metre depth is 6 minus 1 = 5 metres of water pressure. If the groundwater table is at ground level (severe condition seen in parts of Noida and Faridabad), the hydrostatic head is 6 metres. In either case — 5 or 6 metres — the 200 mm Sika Waterbar provides comfortable resistance up to 10 metres head, giving a safety factor of approximately 1.6 to 2.0 against the design groundwater pressure. For deeper basement projects in the NCR (3 basement levels: 9 to 12 metres depth) where the head could approach or exceed 10 metres, specify the 300 mm Sika Waterbar with its higher anchorage resistance, or supplement with the Sika injectable hose system for a dual-barrier joint waterproofing system. Always consult the geotechnical report (site investigation report) for project-specific groundwater table data before specifying waterstop size and system.