4 Signs & Symptoms of Mould Infestation In Your Home

Mould is common in a lot of properties in Sydney and across Australia. It is a structure of fungi that can form as multicellular filaments, reproduced and spread through tiny spores that can travel in the area and grow in poorly ventilated surfaces.

A study conducted by the University of Melbourne in 2020 on the Australian Rental Housing Conditions Dataset found that 27% of renters were experiencing mould in their homes. According to the official WHO guidelines on indoor air quality, an estimated 10-50% of Australian homes are affected by mould.

Mould is found everywhere, thriving in humid and wet conditions with an organic source of dust, dirt, or food. Common household moulds include Aspergillus, Cladosporium, Penicillium, Alternaria, Stachybotrys, and will generally present in black, green, white or brown discolouration, with fuzzy, powdery, or slimy textures. However, not all mould is visible. And while not always ‘toxic’ to your health, all mould should be safely and effectively removed if growing indoors.

If you believe you have a mould problem in your home, the reality is – you likely have a mould issue. But if you want to clarify the signs or identify the source, we’ve compiled a list of common signs and symptoms that you’re dealing with a mould issue.

Signs Of Mould Growing In Your Home

1. Visible Signs of Mould

The most obvious and evident indication that you’re dealing with a mould outbreak is visible signs of mould – it can look like stains or dirt on walls, ceilings, window frames, or a sooty texture within cupboards. Mould can vary in colour and texture – spots, rings, or patches will grow and rapidly spread.

Different types and species of mould can present in different colours too – mould can be black, green, brown, yellow, pink, orange or white fuzzy spots.

As mentioned, it’s not uncommon to notice mould growing on walls, ceilings, and around windows; particularly in dark, damp corners. Common areas to find mould in the household include:

The bathroom: On bathroom walls and tiles, in tile grout, in shower recesses, on the ceiling, and under vanity or bathroom sink areas.

Kitchen: Under appliances (fridge, oven, dishwasher), inside cupboards, under the sink area, and if there’s no ventilation or kitchen excavation fan, above the stove or main cooking area.

Under sink: Mould under the sink or behind the sink cupboard is common – usually caused by poor ventilation, a slow leak, deficient sealing, or just general spills and water.

Wardrobes or cupboards: If your cupboards are jammed with clothes or items it can prevent airflow and create the right environment for mould to grow on clothes, shoes, or the walls of your cupboards.

Under flooring: Mould can grow under timber floorboards, vinyl, laminate, and carpet if moisture becomes trapped and there is not enough ventilation.

2. Musty Odour

A lingering, earthy, or damp smell is usually one of the first signs of mould. The smell is caused by microbial volatile organic compounds (mVOCs) which are released as the fungi grows – resulting in a strong, musty odour that is often compared to rotting wood, wet socks, or earthy soil.

3. Condensation & Water Damage

Surface discolouration or water marks is one of the most indicative signs that there is a mould outbreak. If there is water damage, a leak, or a regularly steamy environment (bathroom, kitchen) that’s causing ongoing condensation, then mould is bound to grow. If you can’t see visible mould but you do experience regular condensation with poor ventilation or have water damage from a leak, it may mean that mould is present.

4. Health Associated Symptoms

Inhaling mycotoxins is anything but harmless – repeated, consistent exposure to toxic mould can have serious effects on your health. The World Health Organisation advises that no level of exposure to mould can be considered ‘safe’ for our health.

According to NSW Health, health effects of mould exposure include a runny or blocked nose, irritation of the eyes and skin, and wheezing. For those with asthma, mould spores can contribute to an asthma attack.

It’s also been shown that repeated exposure and in rare cases mould can develop into a severe mould infection in the lungs. Those with a weakened immune system and with chronic lung diseases are more at risk of mould infection.

Common symptoms of mould exposure include excessive sneezing, coughing, congestion, and eye irritation. Long term exposure can also result in chronic fatigue, headaches, and dizziness.

What are the main causes of mould in the house?

Mould will only grow when there is enough moisture in the air or on a surface. So really, if your home experiences an excessive amount of moisture and it’s not adequately aired out, mould will grow in damp, poorly ventilated areas. The most common causes of mould include:

Leaking roofs
Poor or faulty plumbing
No ventilation (windows, fans, dehumidifiers)
Compromised insulation
Flooding or water damage
Excessive humidity (that’s why Sydney homes are more prone to mould than Melbourne homes)

How is mould confirmed?

If mould cannot be confirmed with the above signs, professional mould testing can identify the specific type and extent of a mould infestation. Mould testing is also used in large scale mould remediation projects where the full extent of the outbreak needs to be identified, particularly if there are airborne spores that continue to spread the bacteria.

How is mould treated?

Mould can be wiped down and removed from a surface, but generally speaking, mould will continue to grow back unless you address the underlying issue. If you have a large mould outbreak in your home, professional mould treatment can get rid of mould from the property, and a mould removalist will be able to provide guidance on addressing the issue – whether you need to start using a dehumidifier, fix leaking pipes or a roof leak, or air the building out more frequently to prevent excessive humidity. When there is a large-scale mould outbreak, professional mould testing and remediation is the most effective way to identify, remove, and remediate the affected areas of the property.

How is mould prevented?

As mentioned, mould is best prevented and treated by keeping your home clean, dry, and well-ventilated to eliminate moisture and prevent mould from growing. Generally, we recommend that our clients:

Use extractor fans in wet areas like the bathroom, kitchen, and laundry
Open windows daily to increase air circulation
Fix plumbing or roofing issues immediately
Keep furniture or objects out of tight spaces to increase airflow
Keep surfaces clean and tidy
Use a dehumidifier where necessary to reduce excess moisture
Clean out your gutters regularly to prevent water pooling or leaks