Mould lurks everywhere: The hidden cost of wet weather and floods

Mould on wall, person with umbrella in floods.
A tiny bit of mould on the plasterboard or gyprock is often the sign of nasties lurking in the wall cavity. (Source: Getty)

Once water recedes from a flooded home, the race is on to dry everything out.

For many victims of the devastating floods in Queensland and NSW, this is the best defence against a second wave of destruction: mould.

For inundated homes, the plasterboard, carpets and insulation will be sodden and anything beneath the waterline will need to be removed to stop mould growth.

But mould, which thrives in the warm, humid weather that’s plagued the east coast for weeks, doesn’t necessarily need extensive flood damage to get going.

Microbiologist and mould expert Wes Black said when it was humid, mould would grow fast. Some species grew exponentially, he said, and could cover a wall within days.

He said a tiny bit of mould on the plasterboard or gyprock was often “just the tip of the iceberg”.

On the other side of the plasterboard, in the wall cavities, he said mould may be growing like crazy.

“Humidity is just so high inside those stagnant areas,” Black said.

Commercial-claims specialist Reuben Rose said heavy rain posed a threat to homes, especially when water seeped under flashings into roof cavities.

“That's when you want to be looking for signs of staining and buckling from the outside of the roof,” Rose said.

Mould remediation can cost hundreds of thousands

Black has been involved in court cases reviewing the costs of remediating mould and said it could run well over $100,000, depending on the severity of the mould infestation.

He said costs for insurers racked up quickly. Things such as temporary accommodation for the family could drive up expenses, he explained.

Rose also said sky-high building materials prices were likely to drive up the costs of mould remediation.

What mould does to you

Black said people were becoming more aware of the health impacts of mould.

People are likely to experience coughs, sneezes, runny noses and asthma flare-ups when exposed to high levels of mould spores.

Some people have more severe reactions, such as an anaphylactic response, like when someone is allergic to peanuts or shellfish.

People need help to dry out their homes

Black would like to see a faster response to help people dry out their homes after floods.

“You need to get things dry sooner rather than later,” he said.

“If you get it done within a few days then there just hasn't really been enough time for much mould to grow.”

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