Mould Found During Snagging: What Happens Next

A dark speckled patch on a bedroom ceiling. A grey bloom at the back of a fitted wardrobe. A musty smell in a bathroom that has never been used. In a city with almost no rain, in a property nobody has lived in yet, mould feels like it should be impossible.

It is not only possible, it is one of the defects we record most often, and it behaves differently from every other item on a snag list. A chipped tile is a defect in itself. Mould is never the defect. It is the visible end of a moisture problem that has been running quietly for weeks or months, and the only response that works is to find the water.

Dubai Municipality publishes a dedicated document on this: Technical Guideline 142, Mould Remediation and Control (reference DM-HSD-GU142-MRC2, issued May 2025) through its Health & Safety Department. The existence of that document is useful to owners for a simple reason. It moves mould out of the category of things a contractor can dismiss as cosmetic and into the category of things with a defined remediation process.

Mould needs three things: a spore, a food source and moisture. The first two are always present in any building — spores are in the air everywhere on earth, and plasterboard, MDF, paint, adhesive and gypsum are all perfectly good food. Moisture is the only variable, and it is the only one worth chasing.

In Dubai, that moisture is almost never rain. It is condensation, and it comes from the same system that makes the building habitable.

Chilled water arrives from a district cooling plant or a chiller and moves through pipework in the ceiling void at a temperature well below the dew point of the surrounding air. Where the insulation on that pipe is incomplete, damaged by another trade during fit-out, or unsealed at a valve or a fitting, the pipe behaves exactly like a cold glass on a table outside in August. It condenses moisture out of the air continuously, all season, onto whatever is below it.

That is the single most important thing an owner can understand about mould in a Dubai apartment. It is not a leak. No plumbing test will find it. No pressure test will fail. Nothing is escaping from inside the pipe. It is an installation defect producing water indefinitely without a single drop coming out of the system, and it will keep producing it until somebody opens the ceiling.

The second common mechanism is a wet area that was tiled before the waterproofing membrane was ever tested. Tiles do not keep water out. Grout does not keep water out. The membrane underneath does, and by the time a mark appears on the other side of the wall, it has usually been compromised for a long time.

The most common response we see from a rectification team is a wipe with bleach and two coats of paint. It looks resolved for roughly one cooling season.

Proper remediation, in the sequence recognised internationally and reflected in Dubai Municipality’s guidance, works in a different order entirely. The moisture source is corrected first. Everything after that is cleanup, and cleanup carried out before the source is fixed is wasted money.

Beyond that, a competent remediation involves containing the affected area so spores are not distributed through the rest of the property while work is under way, removing porous materials that cannot be cleaned rather than attempting to treat them, cleaning non-porous surfaces properly, drying the area fully and verifying that it is dry with instruments rather than by eye, and inspecting again afterwards to confirm the area is clear.

The verification step is the one that gets skipped, and it is the one that matters to an owner. Without a post-remediation check, you have a contractor’s word that a concealed area is now dry.

We inspect — we never repair. That matters here more than anywhere. When we tell a developer that a condensation source is still active behind a ceiling that has just been made good, nobody can argue we are angling for the remediation contract, because we do not take remediation contracts.

If the property is newly handed over and the mould traces back to an installation defect — missing insulation, failed waterproofing, a balcony draining the wrong way — then yes, this is a defect to raise with the developer, and the earlier it is raised the better.

The practical problem is timing. Condensation-driven mould needs a full cooling season to become visible, which routinely puts the first appearance well after the owner has already signed the acceptance. That is precisely why a thermal survey before you sign is worth more than any amount of argument afterwards: it finds the cold pipe in the void while the defect is still somebody else’s to fix.

On resale stock, none of that applies. Whatever is behind the ceiling on the day the transfer completes is yours, which is the reason a pre-purchase defect assessment on an older apartment pays for itself so reliably.