That musty smell in the hallway. The dark spot behind the couch. The persistent cough that won’t go away. If any of these sound familiar, you could be living with a mould problem and not even know it. Mould is deceptively difficult to identify — it hides behind walls, under carpets, and in spaces you rarely check. This visual guide will help you spot mould before it becomes a serious issue.
Visual Signs of Mould
Mould presents in many forms, and not all of them look like the dramatic black patches you see online. Early-stage mould can appear as tiny dark specks on grout, slight discolouration on painted surfaces, or fuzzy patches on fabric. More advanced growth shows as spreading colonies of green, black, white, or grey. Look for irregular patterns that follow moisture lines — along window sills, ceiling corners, behind furniture against cold exterior walls, and around plumbing fixtures.
An important distinction to understand is the mould vs mildew differences. Mildew sits on surfaces and wipes away easily, while mould penetrates into materials and requires more aggressive treatment.
The Smell Test
Often, you’ll smell mould before you see it. A persistent musty, earthy odour — similar to damp forest floor or old books — is one of the most reliable indicators of hidden mould growth. If a room smells musty despite regular cleaning, mould is likely growing somewhere out of sight. Common hidden locations include inside wall cavities, beneath floor coverings, inside HVAC ductwork, and behind cabinetry.
If you can smell it but can’t find it, it’s time to book a mould inspection. Professional inspectors use moisture meters, thermal imaging, and air sampling to locate mould that’s invisible to the naked eye.
Moisture Indicators
Where there’s persistent moisture, mould will follow. Watch for these warning signs: peeling or bubbling paint, warped or buckled flooring, water stains on ceilings, condensation on windows, damp patches on walls, and rust on metal fixtures. Each of these indicates a moisture problem that could already be supporting mould growth.
take our mould risk assessment to evaluate the moisture conditions in your home and determine whether a professional inspection is warranted.
Health Symptoms as Indicators
Sometimes your body detects mould before your eyes do. Unexplained allergic symptoms that improve when you leave home and worsen when you return are a classic indicator of indoor mould exposure. Watch for persistent sneezing, runny nose, itchy eyes, skin rashes, and breathing difficulties. If multiple household members are affected, indoor mould should be high on your list of suspects.
Room-by-Room Inspection Guide
Start your inspection in the highest-risk areas. In bathrooms, check grout lines, silicone seals, ceiling corners, and behind the toilet. In bedrooms, inspect behind furniture against exterior walls, inside wardrobes, and around windows. In kitchens, check under sinks, behind the fridge, and around the dishwasher. In laundries, examine behind the washing machine and around the dryer vent. Don’t forget the garage, subfloor area, and roof cavity.
When to Escalate
If you find mould covering an area larger than a standard dinner plate, if it’s growing on porous materials like drywall or timber, or if you suspect hidden mould behind walls, when to call a professional. DIY removal of small surface mould is feasible, but larger infestations require professional equipment and protocols to prevent cross-contamination during removal. The earlier you act, the less expensive and disruptive the remediation process will be.
Need Professional Help?
If you’re dealing with mould in your home, don’t wait for it to get worse. Our Hobart-based mould removal specialists are ready to help you reclaim a safe, healthy living environment. Take our free mould risk assessment to understand the severity of your situation, or contact us directly for a no-obligation consultation.