Terrace Waterproofing

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

Where it applies. Exposed RCC terraces and roof slabs — accessible or not, tiled or bare — where the inspection shows the slab is structurally sound and the problem is the waterproofing layer, its junctions, or the falls. It is not the right answer where the slab has no fall or a reverse fall; that needs a screed laid to a fall first, and we say so at inspection rather than coat over it.

Preparation. This is where terrace jobs are won or lost, and it is typically 40 per cent of the labour. Existing loose or debonded layers are removed — overcoating a delaminated membrane buys one monsoon. The surface is ground or water-jetted to remove laitance, dirt and biological growth. Cracks are cut out to a V profile and filled with a polymer-modified mortar. A 50 mm coved fillet is formed at every parapet junction, upstand and penetration, because a coating taken straight round a 90° angle cracks there first. Rainwater outlets are cut back so the membrane can be dressed into the body of the outlet, not stopped at its rim. Every pipe, tank support, railing post and dish mount is treated as an individual detail.

Application. A primer appropriate to the substrate and the system, then the membrane in at least two coats laid at right angles to each other, with a reinforcing polyester fabric bedded into the first coat at all junctions, outlets, penetrations and repaired cracks. Coverage is controlled by weight — kg per m² per coat — and checked against the drum count for the area, not applied by eye. We record the dry film thickness achieved and report it, because thinning the applied material is the commonest way a terrace job is quietly cheapened.

Curing and access. Between coats, 6 to 24 hours depending on the system and the weather. Full cure and light foot traffic at around 7 days; the terrace should not be loaded, tiled or trafficked by trades before then. The substrate must be dry at the start and the forecast clear for the curing window — which in Pune realistically means completing before the second week of June or waiting until October. Emergency leak-stopping can be done in the monsoon; a full re-coat cannot.

Testing and warranty. Outlets are plugged and the terrace flood-tested with the ceiling below under observation before handover. A terrace that has not been flood-tested has only been painted. Eligible completed work carries a written ten-year applicator warranty from Leakproofs by Betterwork on the treated area, issued after the test passes, with exclusions stated on the estimate.