What causes mould

What Causes Mould

Identifying and Treating Mould: A Comprehensive Guide


We all know the telltale odour of mould and mildew. This musty smell makes an otherwise pleasant home feel less than welcoming. The source and culprit of this mouldy smell is often found in a home’s most unexpected place.

Perhaps the most difficult and costliest to remove is mould from a subfloor or crawlspace area. Mould can wreak havoc in this unseen place where homeowners rarely visit.

Breaking the Myth

People commonly believe that if they don’t go into their subfloor area, they won’t have to worry about potentially being exposed to mould. However, this is not the case. Air in your subfloor automatically becomes circulated throughout your home. We all know that heat rises, so when this warmer air rises up, all of the mould particles travel along with it. In fact, 60% of your subfloor air freely circulates throughout your home.

Identifying Mould

A type of fungi, mould is not a plant, but is instead an “opportunistic organism.” Mould routinely disperses its spores through the air. Forever seeking a way to grow and reproduce, mould simply needs water, a food source (soil) and warm temperatures to thrive. In some cases, mould can begin growing incredibly quickly, sometimes within 24-48 hours.

Mould is found both indoors and outdoors. It can enter your home through windows, vents, open doorways, and heating and air systems. Mould is so versatile that mould in the air can attach itself to clothing, shoes, bags and pets.

Subfloor mould can be found in many colours,  but whatever the colour of the mould growing in your home, remediation or removal should be the priority.

Possible Causes for Mould Growth

Particularly in wet climates, soil that is left exposed in a subfloor will often propagate mould growth. Excess moisture combined with limited airflow creates the right recipe for mould to grow.  

Since mould does not require sunlight to grow, a dark crawl space is a perfect place for it to grow. Moisture and dead organic matter such as wooden floor joists provide an environment where mould thrives.

 Controlling Mould Amplification

Firstly, inside your home, you can control the growth of mould by controlling humidity levels. Any flooding that happens must be thoroughly cleaned and dried afterwards. Promptly fixing leaky roofs, windows and pipes are important. Ventilating shower, laundry and cooking areas is also vital in controlling mould development. For mould inside of the bathroom area, clean your bathrooms with cleaning supplies designed to kill mould

Should you have any carpets or upholstery that have become soaked, it would be best to remove them.

Signs of a Mould Problem in a Home

A musty smell that just won’t go away

Water stains or green/pink/black spots around the baseboards

Deterioration of the home’s structure itself

Warped, saggy floors or bubbling wallpaper

Unexplained illnesses in the home’s inhabitants

Potential Dangers of Mould Exposure

Sensitive individuals can quickly feel the effects of mould growing in their home. Allergic reactions that are commonly experienced include a persistent cough, runny nose, itchy eyes and skin irritation. Worse cases include people developing asthma when they never had it before. The development of pneumonia in otherwise healthy individuals has also been reported.

According to the Australian Department of Health, they advise that the World Health Organization has concluded that there is an association between mould and asthmatic conditions, allergic alveolitis and mould infections, in those individuals who are susceptible to them. 

You may be wondering, “How much mould is enough to worry about?” The answer is that regardless of the colour or the amount of mould growing, no amount is safe.

The Domino Effect

When moisture invades a subfloor, a condition called rising damp can develop. This happens when moisture moves from the ground and travels upward to other structures within the home. This natural flow of moisture can begin to cause disturbances in the subfloor, beams and foundation.

If left unchecked, rising damp can allow the water to rise through the foundation and eventually into the interior of your home, where it becomes visible. Structural damage, sagging floors or eventual collapse are all a possibility when rising damp takes over.

Treatment and Prevention of Subfloor Mould

Let’s say you have found mould in your crawlspace. What can be done about it? Identifying and correcting the moisture source is important, this can be achieved with drainage, waterproofing and sealing and ventilation. Encapsulating a crawlspace can also be a method to prevent mould in the first place. As you guessed, controlling moisture is also key.  

Mould in the subfloor area must be physically removed – there is no magic gas or vapour that will permanently remediate mould


Although the subfloor of your home is an area that is often dirty, cramped, and full of critters, it is essential to inspect it for signs of mould. The potential risks of having mould propagating in your crawlspace include having it impede on your health and quality of life. Having a professional inspector come to your home and look for potential mould problems will help ensure that you and your family can thrive in the safest of environments. 

For a professional inspection call PureProtect on 1800 664 602