Mould in carpet is easy to miss. It starts underneath, in the underlay, where nobody looks, and by the time it is obvious on the surface it has usually been growing for a while. In a humid Sydney summer it only needs a day or two of trapped moisture to take hold. Here are the four signs worth acting on, and what each one means.
1. A musty smell that comes back after you clean
This is the earliest sign and the one people most often explain away. A damp, earthy smell that is stronger on humid days, stronger in a closed room, and stronger near the floor. If you shampoo the carpet and the smell is gone for a week and then returns, the source is not on the surface. It is in the underlay or the subfloor, and surface cleaning will never reach it.
Worth checking: does the smell get worse after rain? That points to water coming in from outside rather than a spill.
2. Discolouration you cannot lift
Mould shows up as patches rather than lines. Green, black, white or a dull yellow-brown, often with a soft edge that fades outward rather than a hard mark like a spill. Traffic-lane soil follows the path people walk. Mould does not. If a patch is in a corner, behind a door, under a window or beneath a piece of furniture that never moves, and it will not come out with normal cleaning, treat it as suspect.
3. The carpet feels damp when it should not
Press your palm flat on the carpet in a few spots around the room and compare. A patch that feels cooler and heavier than the rest is holding moisture. Common causes are a slow leak from a nearby wet area, a failed seal on a sliding door, rising damp through the slab, or a carpet that was cleaned and never dried properly.
That last one is more common than it should be. A cheap clean that soaks carpet and leaves it wet for two days is a good way to create the problem you were trying to fix. Truck-mounted steam carpet cleaning uses a high-lift vacuum pass so most of the water comes straight back out.
4. Symptoms that ease when you leave the house
Blocked nose, itchy eyes, coughing or a headache that settles when you are out and returns when you get home. Mould spores are a known trigger for allergic reactions and can worsen asthma. This is not a diagnosis, and plenty of other things cause the same symptoms, but if it lines up with a musty room it is worth investigating. Anyone with ongoing symptoms should talk to their GP.
What to do about it
Deal with the water first. Cleaning mould without fixing the moisture source just resets the clock. Find the leak, improve ventilation, run a dehumidifier if the room is closed in.
For a small, recent patch, dry the area thoroughly and get air moving. Do not scrub vigorously with a dry brush, which flicks spores into the air. Do not tip bleach on carpet either; it will not penetrate to the underlay and it will take the colour out.
For anything larger than about a hand span, or anything that has been damp for more than a couple of days, get it looked at. In many cases the carpet can be saved. Where water damage is the cause, our flood and water damage service lifts carpet, dries the underlay and subfloor with air movers, and treats the affected material. Where the trigger is allergy-related, allergen treatment is applied after the carpet is clean and dry.
Preventing it in the first place
Clean up spills straight away and blot rather than rub. Keep bathroom and laundry doors closed and extractor fans running. Open windows on dry days. Move heavy furniture occasionally so air reaches the carpet under it. And when you have carpet professionally cleaned, ask how long it will take to dry — a good answer is four to six hours, not two days.
Adam’s Carpet Cleaning has been family-run since 2004, with IICRC-certified technicians and more than 25 years in Sydney homes. If you have found damp carpet and you are not sure how far it has gone, ring 1300 309 276 for emergency and same-day service, or ask for a free quote. Cleaning starts from $40 to $60 per hour, with a two-bedroom home from $120 and a three-bedroom from $150.
Related reading: useful tips to remove carpet stains and pet stain and odour removal.
