Cracks in Walls & Slabs

What causes it

Structural and shrinkage cracks that let water in. Sealing without identifying which type you have simply moves the problem.

Not every crack leaks, and not every crack matters — but the ones that do need to be told apart before anything is filled.

• Plastic shrinkage cracks — fine, shallow, map-patterned, formed in the first days after a pour. Rarely structural, but on a terrace they are a direct water path into the slab.
• Drying shrinkage cracks — straight, often at changes of section or around openings. Stable once the concrete has dried, so they can be filled and will stay filled.
• Thermal movement cracks — these open and close on a daily cycle, which is why a rigid filler pops out of them within a season. Common along long parapet runs and at roof-to-wall junctions.
• Structural cracks — wider at one end, sometimes stepping through masonry, occasionally with displacement. These need an engineer’s view before any waterproofing, not a coating over the top.
• Corrosion cracking (rust jacking) — cracks running parallel to and directly over reinforcement, often with rust staining and later spalling. The steel is expanding as it corrodes; filling the crack without treating the steel accelerates the damage.

The practical test is movement. A crack that has been stable for years is a filling job; one that reopens every summer needs a movement-tolerant detail, not a stronger filler.

How we identify the real source

Water travels. The stain on a ceiling is frequently metres from the actual point of entry, which is why we deep-scan the structure before recommending treatment rather than working from the visible damage alone.

How we treat it

We establish depth, activity and whether reinforcement is involved before specifying.

• Static, non-structural cracks — cut out to a V or U profile to a sound edge and filled with a polymer-modified repair mortar, then over-banded with reinforcing fabric under the waterproofing layer. Filling at the surface without cutting out is why most crack repairs fail.
• Active or moving cracks — treated as a movement joint: a bond-breaker at the base so the sealant can stretch, a movement-tolerant sealant, and a coating with genuine elongation over the top. Never a rigid filler.
• Cracks passing water under pressure — injection grouting. PU expands on contact with water and is injected against the flow to stop it; epoxy is used where the section must also be structurally re-bonded, and it needs a dry or nearly dry crack, so it follows PU rather than replacing it. Priced per point, typically ₹650–1,400 depending on depth, access and grout type.
• Corrosion cracking — concrete broken back past the corrosion, steel cleaned to bright metal and treated, section reinstated in a repair mortar, then waterproofed. Treating the crack alone leaves the mechanism running.
• Structural cracks — referred for structural assessment first. We will say so rather than coat over a question we are not qualified to answer.

What it costs

Use the cost calculator for an indicative range, or book a free inspection for a written estimate.