A renovated subsale flat in Kota Damansara came with a history nobody mentioned. It was in the ceiling and inside the cabinets.

KOTA DAMANSARA, Selangor. A subsale flat of about a thousand square feet, bought with a renovation already done, is the most common kind of home in the Klang Valley and the one most likely to arrive with a history nobody mentioned. The owner, whom we will call Mr. Yap, had a musty smell he could not shift and a ceiling that never quite looked dry. On Friday, 19 June 2026, a Cleanaholics inspector spent the afternoon finding out how much of the flat's history had come with it.

The short answer, from the report's first page: extensive hidden mould throughout, black mould in two rooms, and an active water leak from the unit above.

What you could see, and what you could not

In ordinary light the problem showed itself in the usual places. Grey-black spotting on a wall below a yellow water stain. Grey-green speckling concentrated along the cornice where wall meets ceiling. Diffuse mould and staining around a pendant light. Grey spotting on the ceiling above the storage shelving, and speckled growth near a beam, heaviest to one side. Five points where growth had broken the surface.

Then the lights went off and the 365-nanometre lamp came out, and the five points became the whole flat. Fluorescing patches above the skirting. Widespread fluorescence along a ceiling track. Scattered speckles across the wall by the window and a denser cluster toward its lower corner. Dense colonisation across the plaster of a ceiling under a beam. Below a piece of artwork, vertical fluorescing streaks where water had run down the wall. A circular halo on one wall, a bloom spreading outward from a moisture source, and another on a dark surface beside it.

The survey went inside the cabinetry. The exterior of a display cabinet fluoresced in speckles and streaks. The top of it fluoresced around the objects stored there. A drawer edge carried fluorescing particulate along its shelf. Inside a kitchen cabinet, the speckling sat on the shelf beside the wine glasses. A countertop was dusted with residue across its surface. And in the bedroom, the side panel of the mattress showed faint fluorescing staining and specks.

Room by room, the report set it out. The shoe rack at the entrance was fully contaminated with a thick growth the inspector described, from field experience, as consistent with a common indoor mould, pending laboratory confirmation; the wall opposite carried growth that had plainly been there for some time. The melamine kitchen cabinetry, including above the oven, was full of hidden mould, melamine being a low-cost material that mould favours. The store room was musty, with growth on the walls and in a distinct pattern across the floor tiles. The laundry doors carried mould and its ceiling showed black patches. The office area, built in gypsum board, had mould and yellow staining. The air-conditioning units, the soft furnishings and the mattress all held spores.

Mould is airborne: it spreads as fine dust from space to space, so it is not confined to the rooms where it is visible. With a sub-sale home, much of this was likely present before you moved in and has advanced over the years since renovation.From the report, 19 June 2026

Where the water was coming from

The thermal camera answered the question the ceiling stain had been asking. A large cool zone across the ceiling, down to 22.8 degrees against nearly 28 around it, a clear moisture-affected patch. A cool plume tracking down the wall from the junction above. A cool patch at an upper corner, a cool line along a ceiling seam, a cool patch over a ceiling apex, a cooler band along a corner joint. Every one of them tracked water arriving from above and spreading through the structure.

The moisture meter agreed independently. The ceiling beam read 725 on a scale that ends at 999, well into the Wet band. The walls read 202, wet at the top and drying toward the floor. The toilet area read about 325. The water was entering from above, not rising from below.

The air itself, for once, was not the story. Formaldehyde was negligible, dust within range, the air-quality index in the healthy thirties and forties. The living area read a comfortable 55 per cent humidity. Only the bedroom, at 65 per cent, sat in the band that feeds mould. This was a home whose problem was in its ceiling and its materials, not its air.

Two problems, two owners

The report separated the two things that had to happen, because they belonged to different people. The leak was the building's problem before it was Mr. Yap's. It was coming from the unit upstairs, spreading through the slab by capillary action, and until that source was sealed, the report said plainly, his ceiling and upper walls would keep re-wetting and the mould would keep returning regardless of any surface treatment. It recommended, in writing, that the thermal and moisture evidence be put to the building management so the upstairs source could be traced and waterproofed. No finding of fault; a finding of direction.

The mould was his. The recommendation was a core-level remediation of the whole home, not spot cleaning, because the lamp had shown the contamination in nearly every space and inside the cabinetry: laboratory identification of the mould through the university research partner so the treatment is targeted; a professional organising team and a biohazard team categorising every item as treatable or not, with the owner deciding on each; hospital-grade steam preparation; anti-fungal treatment by fogging and misting, with replacement of the affected melamine and gypsum; an antimicrobial coating; and verification by swab and a second pass with the lamp, under a five-year warranty with a yearly inspection. The two rooms with black mould were to be treated under a separate, stricter protocol with containment, respirators and HEPA extraction.

Our aim is honest: we bring the mould to a controlled, verified level, not an impossible claim of total elimination.The inspector’s position, from the report

What it means for anyone buying subsale

A renovated subsale flat hides its history behind new paint and fitted cabinets, and the cabinets themselves, if they are melamine, are part of the history. The lamp, the thermal camera and the moisture meter, used before the offer is signed or at least before the boxes arrive, tell a buyer what they are actually purchasing. In this flat they told him three things at once: that the mould was everywhere, that the water was coming from upstairs, and that neither of those was his fault.

Reported from the Cleanaholics inspection of 19 June 2026. The client's name has been changed and the building and unit withheld. Mould types are indicative from field observation and confirmed only by laboratory culture; the report makes no finding of fault against any party.