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Dannielle Maguire

Where you should be looking for mould and how long it takes to start growing

Experts encourage people to deal with mould as quickly as possible to stop it from spreading.  (ABC News: Jack Fisher)

With La Niña bringing lasting wet weather and high humidity, many people are finding mould in their homes. 

If you're worried there could be a mould infestation lingering in your home, here's what to do.

How long does it take for mould to grow after wet weather?

Garry Carroll, director of the Australian Cleaning and Restoration Academy, says it really depends on the home, the water exposure and the humidity. 

"Mould can start [growing] from 48 hours sometimes, if it’s got the right conditions," he said.

While there might not be mould in the day or two after heavy rain, a change in conditions — like a humidity hike — can accelerate growth.

Dampness and poor ventilation are risk factors for household mould.  (ABC Radio Brisbane: Hailey Renault)

What are the early signs mould could be an issue?

Look out for dampness, a musty smell and condensation.

Mr Carroll says there are two ways that mould infests properties — high humidity and water exposure.

When water gets into your home from leaks or floods, mould can grow in places that haven't dried out properly.

Mr Carroll says there's a greater risk of mould when the humidity climbs beyond about 70 per cent.

"Once it goes above that, there’s more of a chance of things hitting dew point," he said.

"The air reaches saturation and can’t hold more water.

"Condensation builds up on materials, and then mould forms."

Where are the first places to look?

Any room with a water source in it — bathrooms, toilets and laundries.

Mr Carroll says it's also important to look in bedrooms that adjoin bathrooms.

Look at the entirety of the room, paying extra attention to the corners, ceiling cornices, window sills, carpets and skirting boards.

Mould can be thriving out of sight.  (Supplied)

Where else should I be looking?

Check soft, porous surfaces like couches and mattresses.

But don't just do a quick once-over, inspect hidden places that aren't exposed to the air.

Lift up couch cushions, check underneath mattresses, pull back mattress covers, lift up rugs and look under your doormat.

And check out items that have no airflow around them — look in cupboards, drawers and behind dressers

If you've got an air conditioner, check the filter. 

There's also been reports of people finding mould behind picture frames and mirrors hung on the wall. 

Check anything that doesn't get a lot airflow behind it, like hanging mirrors.  (Supplied)

"Behind a picture frame, there's no airflow," Mr Carrol said.

"There's usually cardboard backing or MDF timber — both of those are very absorbent."

And don't forget to inspect your indoor plants, as they are consistently damp (especially if you're watering them properly).  

I've found mould, now what?

"We recommend that, as soon as you see mould growth, you should act as swiftly as possible," Gerard Murtagh from cleaning company MouldMen said.

"Try and clean those areas, and keep your home dry."

Mr Murtagh says you can clean the mould yourself but if the growth is bigger than a dinner plate, it's best to call in an accredited expert.

Mr Carroll says if you're dealing with surface mould, it can be treated quite easily. 

But if that mould is growing through the gyprock or plasterboards in your home, say from a leak in the ceiling, it's going to be a bigger job.

How do you remove mould?

Mr Carrol says it's important not to just kill the mould, but to remove the dead spores. 

So if you've wiped over some mould, don't use that cloth again because it'll only spread the spores.

The Queensland government says once you've cleaned the mould, you should go over the surface again with a new damp cloth and then dry it with another clean cloth.

Mr Carroll says a stabilised chlorine dioxide is the best commercial product for cleaning mould.

The Queensland government lists the following home remedies for removing mould:

  • a solution of 3 parts vinegar and 2 parts water
  • a solution of 70 per cent methylated spirits and 30 per cent water
  • a solution of tea tree oil and water

How do I dry out my home?

Turning on the fans is a good place to start.

If you've got an air conditioner, run it on dry mode or consider using a dehumidifier.

If the humidity is high, crank up the air conditioner to keep the dampness outside.  (ABC News)

Open up the windows to air the place out, but only if it's sunny and not too humid.

"You can't open windows and ventilate when it's [pouring] down outside, you're only letting high humidity in," Mr Carroll said.

How do I prevent mould?

Keep the humidity out and make sure your home is well ventilated.

Look out for any water leaks, fix them quickly and install exhaust fans in the laundry and your bathrooms.

After you've had a shower, open a window and run the exhaust fan for about 15 minutes to get rid of the steam. 

Freshen up the paint on your walls, because that'll provide a good protective barrier to prevent porous wall materials from sucking in moisture — the Queensland government suggests adding an anti-mould solution to the paint to help slow down mould growth. 

Keep your gutters clean, because this stops rainwater pooling during heavy downpours. 

Check the external walls of your home, clearing plants, soil and leaf litter from weep holes

And keep in mind that plants growing on or close to external walls can promote moisture. 

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