Mould, a common fungus, exists naturally in many environments. It reproduces by releasing microscopic spores that travel through the air and settle on surfaces. When spores encounter moisture and a food source, they grow and multiply. Early identification is important for a healthy indoor environment.
Recognizing Mould by Sight and Smell
Mould appears in many forms and colors. Patches might look fuzzy, slimy, powdery, or cotton-like, depending on growth conditions. While often black or green, mould can also be white, orange, brown, or grey spots or patches. Its color is not a reliable indicator of its specific type or potential harm.
Mould also produces a distinctive odor. A musty, earthy, or damp smell often signals its presence, even when not visible. This odor is caused by volatile organic compounds (MVOCs) released during mould growth. A persistent musty smell can indicate hidden mould growth, such as behind walls, under flooring, or within ventilation systems.
Where Mould Commonly Grows
Mould thrives in environments with elevated moisture levels, making certain home areas susceptible. Bathrooms are common sites, with mould appearing on shower tiles, around bathtubs, and within grout lines due to constant humidity and water splashes. Kitchens can also harbor mould, especially under sinks where leaks occur, around dishwashers, or near refrigerators that produce condensation. Basements, attics, and crawl spaces are also prone to mould growth due to higher humidity, poor ventilation, and water intrusion.
Signs of water damage indicate hidden mould. Water stains on ceilings or walls, peeling paint, discolored drywall, or warped wooden flooring all point to past or ongoing moisture issues that provide ideal conditions for mould development. Even if these areas appear dry, mould could be growing within affected materials.
Mould can also grow in less obvious, hidden locations. It may grow behind drywall, under carpets, or inside wall cavities where moisture has accumulated. HVAC ducts can circulate mould spores throughout a home if growth occurs within the system. These hidden areas often remain unnoticed until a musty smell becomes noticeable, indicating active mould colonies.
Advanced Detection and Professional Help
While visual and olfactory cues are often the first indicators, some homeowners consider using DIY mould test kits. These kits typically involve taking air or surface samples using a petri dish or swab, then cultured at home or sent to a lab. However, these kits have limitations; they may not accurately identify the mould type, nor reliably indicate the extent or concentration of growth. False positives or negatives can also occur, leading to misinterpretations.
Seeking professional assistance for mould identification is recommended in specific scenarios. If a visible mould patch covers an area larger than 10 square feet, or if a persistent musty smell exists without visible mould, it suggests an extensive or hidden problem. Professionals should also be consulted if mould reappears shortly after cleaning or following significant water damage, such as a flood or burst pipe. If individuals are experiencing unexplained health symptoms linked to mould exposure, professional identification can help assess the environment.
Professional mould inspectors employ various methods to identify and assess mould issues. They conduct thorough visual inspections, utilize moisture meters to detect hidden moisture in building materials, and may take air samples to determine spore concentrations. Surface samples can also be collected from suspected areas to identify mould species. These assessments provide an accurate understanding of the mould problem, guiding appropriate next steps.