Injection Grouting (Pressure / Chemical)

This treatment is specified where the inspection shows it is the right answer for the problem found.

Where it applies. Cracks, construction joints, honeycombed concrete and voids that are actively passing water, and situations where the water-facing side cannot be reached — basement walls behind soil, retaining walls, lift pits, water tanks in service, slab-to-wall junctions, and leaks between floors of an occupied building. Injection treats the crack through its full depth from whichever side you can get to, which is why it is often the only option. It is not a substitute for a membrane on an open surface, and any contractor proposing injection across a whole terrace is proposing the wrong thing.

Choosing the grout. PU (polyurethane) grout for active, running water: it reacts with water and expands to fill the void, so it is injected against flow and stops it. It stays flexible, which suits a joint that moves, but it is a water-stop rather than a structural repair. Epoxy grout where the crack is structural and the section needs to be re-bonded to its original strength — it is rigid and requires a dry or nearly dry crack, so it follows PU rather than replacing it where water is present. Acrylic and microfine cement grouts for larger voids, honeycombing and curtain injection behind a wall. The diagnosis determines the grout; we state which one is being used and why on the estimate.

Preparation and application. The crack is mapped and its depth and activity established. Injection packers are drilled at an angle to intersect the crack at depth, spaced at roughly half the section thickness — typically 150 to 300 mm apart — and staggered on alternate sides where access allows. The crack face is surface-sealed so grout builds pressure inside it rather than escaping. Injection then runs from the lowest packer upward, at controlled pressure, holding each port until grout shows at the next one — that is the confirmation the crack is filling continuously. Pumping to a pressure figure alone tells you nothing about coverage.

Curing and finishing. PU reacts and expands within minutes and the leak generally stops during injection. Epoxy cures over 24 hours to handling strength and 7 days to full strength. Packers are cut off and the ports and surface seal are made good with a repair mortar once cure is complete, then the area is finished to match.

Pricing and warranty. Injection grouting is priced per injection point rather than per square foot, typically ₹650 to ₹1,400 depending on section depth, access and grout type — so the estimate states the number of points, and a revision is agreed with you if the crack proves deeper or longer than surveyed. The treated area is water-tested afterwards by reproducing the original leak condition. Eligible completed work carries Leakproofs by Betterwork’s written warranty on the treated area.