After the deluge: when mould takes hold


An example of black mould - not from the affected flat

With impeccable timing, given the OCN webinar on waterproofing today (Wednesday, April 6), here’s a Sydney Morning Herald Lifestyle section report by Sue Williams about how mould can come into your home … and how to get rid of it.

After the floods, the teeming rain and the sticky humidity of such a long, wet, La Niña summer, it’s the uninvited visitor everyone dreads – mould.

Open the wardrobe and it’s there, feasting on a favourite leather jacket and pair of shoes. Check the walls under windows, and there could be a tell-tale dark speckled stain. And what is that horribly musty smell coming from the bathroom?

“It can be very depressing living with damp and mould,” says Jo Rosenthal, 62, whose apartment in Sydney has been leaking into overflowing buckets in the torrential rain.

“It does affect your mood both physically and mentally. My husband is an asthmatic and my immune system has been affected from the stress of living with damp and mould. If I get a cold these days, I’m down for three weeks.”

There’s plenty of evidence now that mould – minute microorganisms growing on any moist surface – can have an impact on health, sending clouds of invisible particles of mould into the air that can cause allergies, asthma, infections, itchy eyes and skin,  and various breathing problems. 

The World Health Organisation (WHO) attributes much of the world’s 300 million cases of childhood asthma to living with indoor dampness and mould.


Yet mould only becomes a problem when there is moisture, and the inability for it to escape, says Dr Michael Taylor, a microbiologist at Flinders University in South Australia, with a special interest in fungi, spores, mould and mushrooms.

“After large rainfall or flood events, porous materials in buildings like wood, insulation, carpet and furnishings absorb a lot of water. This water can then support the growth of fungi and fill cavities and hidden areas with very humid and stagnant air – perfect conditions for problem moulds such as Stachybotrys, the toxic black mould.”

Most of the time, though, the fungi that turns up after minor water damage won’t poison us or cause infection, but will have an unpleasant smell, can cause allergy-like symptoms and will grow unless treated.

The first step is always to fix what caused the problem in the first place, whether a leak somewhere, with an ill-fitting window frame, a sliding door that has gaps in the tracks, a crack in the ceiling or a gap in the roof, or a more serious problem like rising damp.


Then we can tackle the mould itself. For minor cases with clothes and soft furnishings, thoroughly washing and drying, or dry-cleaning items, should fix the problem, advises Jan Fleming, the co-author with Shannon Lush of the housekeeping Bible, Spotless.

“For hard surfaces and leathers, put a quarter of a teaspoon of oil of cloves in a litre of water and spray the area, leave for 24 hours, then spray again and wipe the mould away,” Fleming says.

“A lot of people go for bleach, but that just makes the area white so you can’t see the mould – but it’s still there. Oil of cloves will kill it. But for more serious mould issues, get expert help.”


One of those experts is MouldMen founder and CEO Gerard Murtagh who, as a quick rule of thumb, says if the damp comes from the sky or humidity, then you can let it dry. If it comes from floodwaters, then throw it out.

“There are so many pathogens in flood waters, mud and black sludge, from faeces, dead animals and silt, and these can make you very sick,” he says. “So you need to discard everything that’s come into contact with the waters.

“If walls are damaged, these may need to be cut out too at least 50cm above the waterline, because the plasterboard and insulation will have absorbed the water and it might be accumulating in the cavities behind. But if it’s just a result of humidity or rainwater, then you can dry it then treat it.”

Ventilation is always key too. Opening windows and doors might let more damp air in, but that’s at least diluting the mould spores that are already in the air.

Mould Buster CEO Matt Reardon says a lot of people are seeing spots of mould at the moment and are panicking, but minor cases are just symptomatic of our climate. 

“A little mould can be normal with so much moisture around, and easily treatable,” he says. “White vinegar can be very useful – even though it can make a smell like a fish and chip shop – and research has found microfibre cloths are great for kind of plucking mould from surfaces. But ventilation and fixing leaks are key.”

This story first appeared in the Lifestyle section of the Sydney Morning Herald.

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