Ceiling Leakage & Dripping

What causes it

Dripping or sagging ceilings, falling plaster and stained POP — the visible result of a leak that started somewhere else.

A ceiling stain is an exit, not an entry. Water entering a slab travels along the top of the reinforcement, down a service conduit or across a shaft, and emerges at the lowest or weakest point — often metres from where it got in. Treating the stain treats the symptom, which is why so many ceiling repairs come back.

What is usually above it:

• A terrace or roof, if the top floor is affected and the leak follows rain.
• A bathroom, kitchen or utility in the flat above, if the leak follows use rather than weather.
• A concealed plumbing run in the slab or the shaft, if it never stops at all.
• A balcony above, where the fixed edge of a cantilever cracks and the soffit below stains first.
• An AC drain line discharging onto a slab instead of into a drain — a surprisingly common and very cheap fix.

Where the ceiling has begun to spall with reinforcement showing, the leak has been running long enough to corrode steel. That is now a structural repair with a waterproofing component, not the other way round, and it should not wait.

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 work from the source down, never from the stain up.

Thermal imaging maps the saturation behind the finish — nearly always wider than the visible mark, and its shape points back toward the entry. Moisture readings at depth confirm it. Supply and waste lines are isolated to rule plumbing in or out. Where the path is still ambiguous we wet one zone at a time — a single terrace bay, one balcony, one bathroom — and watch below.

Then the source is treated: junction and outlet re-detailing, membrane repair or replacement, wet-area tanking, injection grouting at a crack or joint, or plumbing correction. Where the water-facing side genuinely cannot be reached, a negative-side crystalline system is applied from beneath, because it resists pressure through the concrete’s pore structure rather than relying on adhesion — an adhesive coating on the underside is simply pushed off.

Only once the ceiling has stayed dry through a reproduced leak test do we make it good: spalled concrete cut back past the corrosion, reinforcement cleaned to bright steel and treated, the section reinstated in a polymer-modified repair mortar, then skimmed and painted. Patching a ceiling while water is still arriving is cosmetic, and it returns within weeks.

What it costs

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