Bathroom Leakage Problems

What causes it

Damp patches on the ceiling below a bathroom, usually from failed sunk-slab waterproofing or leaking concealed plumbing.

Bathroom leakage usually reaches us as a complaint from the flat below rather than from the bathroom’s owner. Three faults produce an identical ceiling stain and cost very different amounts to fix:

• Failed floor waterproofing. Tracks with use — worse after showers, better when the flat is empty. The membrane sits under the screed, so it cannot be reached without lifting the floor.
• A plumbing leak. Supply line, waste connection or the floor trap. Continues through a dry fortnight and does not vary with how much the bathroom is used.
• The shared wet wall or service shaft. Many Pune flats put the bathroom back-to-back with a kitchen or against a stacked shaft; a failure several floors up arrives at the base of your wall.

Beyond those, the recurring detail failures are: waterproofing stopped at 300 mm when the shower zone needed full height; the membrane stopped at the rim of the floor trap instead of dressed into its body; pipe penetrations packed with mortar rather than sealed with a collar; and a threshold detail that lets water track out under the door frame into the passage screed.

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

Plumbing is isolated and tested before anything is quoted, because there is no waterproofing system that resists a live pipe leak — and if that is the answer, it is a far smaller job than the one most people are braced for.

Where the membrane has genuinely failed, a coating over the existing tiles is not a repair. The wet area comes back to the structural slab across its full extent, not just the visibly failed part. Fall to the drain is checked and re-screeded if it runs the wrong way, cracks are cut out and filled, a coved fillet is formed at every wall-to-floor junction, the drain body is exposed so the membrane can be dressed into it, and every penetration gets an individual sealing collar.

A cementitious polymer-modified or PU tanking membrane then goes on in two coats at right angles with reinforcing tape at all corners and penetrations — full area on the floor, at least 300 mm up the walls, full height in the shower zone.

Expect the bathroom to be out of use for five to seven days including the test and retiling. Before tiling we plug the drain, flood to 25 mm and hold it for 24 hours with the ceiling below watched; where the bathroom sits above another flat we arrange for that owner to be present, which also settles the liability question in a society. The ceiling below is made good only after the test passes.

What it costs

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