How and when to remove mould from your home

After a wet few weeks, one task you may be facing is cleaning up mould in your home.

Mould problems can come weeks, sometimes even months, after heavy rains, Dr Mark Donohoe told ABC Radio Sydney, who is a GP specialising in environmental medicine.

While he says mould "typically" doesn't do any great harm, it becomes more of a risk the longer we wait to deal with it, increasing our exposure.

It can trigger nasal congestion, sneezing, coughing, respiratory infections and worsen asthma and allergic conditions.

We spoke to the experts for their tips on mould removal from surfaces, and when something requires an expert, or may not be salvageable at all.

What is mould?

Mould is a type of fungi, and is present in the natural environment.

It can be black, grey, green or white. Damp environments, like inside your home after wet weather, typically will increase the amount of mould spores.

What can and can't be saved

If your house has been subject to flooding, a porous surface like plasterboard likely won't be recoverable, says Brad Prezant, a certified occupational hygienist.

So mould on surfaces like carpets and furniture may also mean they are unsalvageable.

If you haven't been flooded, but there is moisture present, Mr Prezant says to seek the advice of an occupational hygienist or building restoration professional — especially if there are larger areas of mould.

"When you're in a situation like it hasn't become flooded but maybe there is moisture, then you want a professional to go around with a moisture meter and see what areas require attention."

Those experts can also help if you suspect there is mould in your home, but can't see it.

Jane Whitelaw, a certified occupational hygienist at the University of Wollongong, says you may be able to tackle smaller areas yourself, which we'll get to soon.

Non-porous surfaces like hard plastics will be easier to clean.

But you'll want to address those surfaces made from natural material as soon as possible.

"Anything made of wood or paper or leather or cloth — anything made from natural material is subject to mould degradation," Mr Prezant says.

Drying the surface before mould removal

Before removing mould from surfaces, Mr Prezant says the surface itself needs to be dry and structurally sound — otherwise there is no point.

"If the material is dry, and mould is superficial with no degradation of the material itself … then you need to remove the mould," Mr Prezant says.

Without industrial materials to create an artificially dry environment inside your home, all you can really do is open windows and doors to ventilate the space, Mr Prezant says.

Using exhaust fans in humid rooms of the house like the bathroom and laundry, and making the most of airflow on drier, sunnier days will be helpful, Ms Whitelaw says.

Fixing roof leaks and checking for blocked gutters, for example, will be vital to prevent further moisture getting in.

Cleaning the mould

Wearing protective gear like a mask, gloves and eye protection is advised when cleaning up mould.

Superficial mould can be removed by wiping with a damp cloth.

If product is needed, there are several things you can try.

Ms Whitelaw recommends mixing one part bleach to four parts water. 

"Using a damp cloth, scrub an area with that mixture. Don’t keep rinsing the cloth out — get rid of that cloth — and go again with a new one.

"Microfibre cloths are cheap and great."

She uses this technique on the back of her leather lounge which develops mould in the wetter months.

However, author and cleaning guru Shannon Lush told ABC Radio Sydney bleach may just take the colour out, hiding the mould problem.

She recommends a quarter of a teaspoon of clove oil mixed with a litre of water to clean hard surfaces.

"It doesn’t sound like much … but it's incredibly effective … and it can be dangerous if you do use it stronger than that."

Leave it on for 24 hours and if it doesn't fall off by itself, wipe it down with a cloth and white vinegar mixed with water.

Victoria's Department of Health says most household detergents can also do the job, followed by an anti-bacterial cleaner to kill germs and remove smells.

When small areas of mould return, the health department recommends using the white vinegar solution (one part vinegar to three parts water) or tea tree oil (two teaspoons to two cups of water).

When vacuuming mould, only a HEPA (high efficiency particulate air) filter should be used. 

For any mould situation that looks like it will take longer than an hour to clean, Ms Whitelaw says that's a good sign you need to get a professional in.