Water drips from your ceiling when the unit upstairs showers — how to confirm it, the RM650 flat PU injection fix, the strata rules and honest costs from a Klang Valley contractor.
First, make the situation safe and contained. Put a pail under the drip and move anything damageable out of the zone. If the water is near a ceiling light or fan — and in bathroom-below-bathroom layouts it usually is — switch off that lighting circuit at the DB box until the ceiling is dry. If the plaster ceiling is sagging or bulging, drain it through a small controlled hole over a bucket rather than waiting for it to come down. Photograph and video everything with timestamps, including the moments when the drip is active. Then send a polite message to the upstairs unit — most inter-floor leaks are resolved amicably, and starting with a WhatsApp and a photo works better than starting with a complaint letter. What you should not do yet: repaint, replaster, or accept any quote that starts with paint.
Before anyone drills or hacks anything, confirm the source, because ceiling drips have several look-alike causes. The cheapest diagnostic tool is a notebook: track the drip against what is happening upstairs for two or three days. Inter-floor bathroom leaks follow usage — they appear 10–30 minutes after the upstairs shower runs, peak in the morning and evening bathing windows, and stop entirely when the unit above is empty for a weekend. Rain leaks follow weather instead, pipe leaks follow nothing (they are constant), and aircon leaks follow the compressor.
| What you observe | What it points to |
|---|---|
| Drip starts 10–30 min after the upstairs shower, worst morning & night | Upstairs bathroom floor waterproofing — this guide |
| Drip is constant, day and night, regardless of anything | A pressurised concealed pipe — see the pipe section below |
| Drip only during or after heavy rain | Roof or facade, not the bathroom — see our roof leak in heavy rain guide |
| Drip when an aircon (yours or upstairs) has been running | Condensate line — see our aircon vs pipe leak diagnosis guide |
| Drip stops completely when the upstairs unit goes on holiday | Upstairs usage water — bathroom or kitchen above |
If the pattern matches the first row, you have the classic condo problem — and a well-mapped path to fixing it.
The stain itself carries information. A bathroom slab leak typically shows as a spreading yellow-brown ring or patch, often with white powdery efflorescence (lime salts carried out of the concrete) and sometimes black mould at the edges, and the water smells faintly stale or soapy rather than fresh. Location matters just as much: sketch your ceiling and mark where the upstairs unit's shower area, bathtub, floor trap and toilet sit above it — in most condos the stacked layouts make this easy to estimate. Leaks concentrate under the wet zones: the shower floor, the floor trap penetration, and the wall-floor joint. A stain directly under the toilet line points at the flange or the joint around it. A stain that tracks along the ceiling towards a wall may still start at the bathroom — water follows the slab's slope and rebar before it drops.
Under the upstairs unit's bathroom tiles is (or was) a waterproofing membrane, applied when the block was built. Membranes are consumables: 10–15 years of thermal movement, structural settling and detergent-laden water fatigue them, and they crack first at the stress points — the floor trap and pipe penetrations, the wall-floor joint, and any hairline crack in the screed. Tile grout is not waterproofing; once the membrane below fails, every shower sends water into the screed, where it accumulates and works through the slab's pores and cracks. Renovation is the other trigger: if the upstairs unit re-tiled and the contractor hacked into or skipped the membrane, leaks can start within months. This is why the age of the block and any recent upstairs renovation are the first two questions we ask.
The most commonly sold "fix" for a leak-stained ceiling is skim and repaint, sometimes with a confident-sounding waterproof sealer. It always fails, for a simple reason: the water is still coming. Paint and skim coats sit on the dry side of the slab; they cannot resist water arriving from behind with nowhere else to go. Within weeks the new paint bubbles, the stain bleeds through, and mould returns — except now you have paid twice. Sealers marketed as "damp block" merely delay the visible symptom while moisture spreads laterally inside the plaster. The correct order is unglamorous but non-negotiable: stop the water first, let the slab dry, then repaint. Any quote that starts with paint is a quote for doing this twice.
Polyurethane (PU) injection is the fix-from-your-side option, and for most single-bathroom ceiling leaks it is the fastest and cheapest permanent repair. The process: drill small ports into the underside of the slab along the water paths, inject a water-reactive polyurethane resin under pressure, and let it chase the moisture — the resin expands into a dense foam that fills the cracks and capillary paths the water was using, sealing them from inside the slab. The whole job is done from your unit in half a day, with no hacking, no access to the upstairs unit and no tiles disturbed. ClickBina charges RM650 flat for one bathroom ceiling, with a 6-Month No-Leak Warranty (indicative 2026, Klang Valley) — if the same area weeps again within six months, we return and re-inject at no charge. For the full process, chemistry and honest limitations, see our PU injection guide.
The fix-at-source option is to renew the failed membrane itself: hack up the upstairs bathroom's floor tiles, remove the old screed, apply a new waterproofing membrane properly dressed up the walls and around penetrations, water-test it, then re-screed and re-tile. Done well, it resets the bathroom's waterproofing for another 10–15 years — it is the more fundamental repair, and the right call when the membrane has failed broadly rather than at one point, or when the upstairs unit is renovating anyway. The costs and logistics are heavier: RM2,500–RM6,000 for a typical bathroom (indicative 2026, Klang Valley), four to seven days of work, and the upstairs bathroom out of action throughout — which means it only happens with the upstairs owner's full cooperation. Our bathroom waterproofing guide covers the membrane systems, process and standards to insist on.
| Factor | PU injection (from below) | Re-waterproofing (from above) |
|---|---|---|
| Indicative cost | RM650 flat, one bathroom ceiling | RM2,500 – RM6,000 |
| Access needed | Your unit only | Upstairs unit must agree and cooperate |
| Time | Half a day | 4 – 7 days |
| Disruption | Minimal — no hacking | Upstairs bathroom offline; hacking noise & debris |
| Best for | Localised leaks, active drips, an uncooperative or absent upstairs owner | Widespread membrane failure, or upstairs renovating anyway |
| Warranty / life | ClickBina 6-Month No-Leak Warranty; resin is permanent in sealed paths | New membrane typically lasts 10 – 15 years |
In practice many cases start with injection — it stops the damage now, from your side, at a tenth of the cost — and escalate to re-waterproofing only if the membrane keeps failing in new spots.
In a strata building you are not negotiating from zero: the law leans your way. Under section 142 of the Strata Management Act 2013, damp or water penetration in your ceiling is presumed to come from the parcel above unless proven otherwise — the burden sits upstairs, not on you. The working process: report the leak in writing to your JMB or management corporation, which is obliged to inspect (with the standard inter-floor leakage forms) and determine the cause; if it is the upstairs unit's failed waterproofing, responsibility for repair follows. In reality, a calm WhatsApp to the neighbour plus a JMB inspection resolves most cases without lawyers — but the presumption matters when a neighbour stonewalls. This is deliberately a summary: the full legal playbook, forms, timelines and what to do when the neighbour refuses are in our inter-floor leakage guide. And if you are a tenant rather than the owner, our mould & damp rental responsibility guide covers who pays as between you and your landlord.
A minority of "upstairs bathroom leaks" are actually plumbing, and the giveaway is timing. A pressurised supply pipe embedded in or running under the slab leaks constantly — day, night, holidays — because the pipe is always under mains pressure, and the water is clean and odourless. A waste-pipe joint leaks only when a specific fixture is used and often smells foul. The meter test settles the supply-pipe question: close every tap in the upstairs unit, note the meter reading, wait an hour, and if the meter has moved there is a live pipe leak. Pipe repairs are a different trade and price from waterproofing — injection will not fix a leaking pipe, and honest diagnosis comes first. Our ceiling drip diagnosis guide walks through separating aircon, pipe and slab leaks symptom by symptom.
Once the water path is sealed, wait before making it pretty: the slab and plaster hold a surprising amount of moisture, and repainting too early bubbles even after a successful repair. The practical test is two dry weeks — no new staining, watermark stable, surface dry to touch. Then the cosmetic repair is straightforward and cheap relative to everything above it (indicative 2026, Klang Valley):
| Cosmetic repair | Indicative cost |
|---|---|
| Stain-block, skim & repaint the patch | RM150 – RM400 |
| Replace a damaged plaster ceiling section | RM300 – RM800 |
| Replace a sagging gypsum board panel | RM250 – RM600 |
| Repaint the whole ceiling / room for an even finish | RM400 – RM900 |
Use a stain-blocking primer over the old watermark — ordinary emulsion lets tannin stains ghost through even when the slab is dry. Our ceiling leak repair guide covers the full repair sequence from drip to final coat.
ClickBina handles inter-floor bathroom leaks across the Klang Valley end to end: honest diagnosis first (send us a photo and a note of when it drips on WhatsApp and we'll tell you honestly what it is), PU injection at RM650 flat for one bathroom ceiling with a 6-Month No-Leak Warranty, full upstairs re-waterproofing when that is genuinely the right fix, and the plaster and paint to finish. We will not sell you a RM5,000 re-waterproofing job when a RM650 injection solves it — and we will tell you plainly when it is a pipe and you need a plumber instead. Most Klang Valley appointments are available within one to two days.
Tell us what you need — we reply within the hour.