You can often smell and sense damp before you can see it. When it finally does appear it’s a costly, unhealthy nuisance that has to be dealt with fast.
Rising damp destroys the comfort of a home, creating musty smells and causing or aggravating asthma and allergies.
If left untreated, rising damp can carry soluble salts up into the masonry, causing what’s known as efflorescence, which can eventually destroy foundations and in severe cases result in once solid masonry eroding and crumbling away.
Right now parts of Australia are in the grip of a rising damp and mould scourge.
According to Scott Lambert, national managing director of Dr Damp, it’s the worst he’s seen in 15 years of business.
A damp epidemic
‘Three years ago, one in 20 of the homes we visited had mould, now it’s four out of five,’ says Dr Damp’s Scott Lambert.
‘It’s an epidemic.’
‘Sydney seems to be the worst because of recent rain and heat.
‘Melbourne’s had a drenching but as it’s colder the problem isn’t as bad.’
Scott says the parts of Australia where heat and moisture are most common, such as the Northern Territory and tropical Queensland, don’t have mould problems.
‘Places like Darwin with a wet, humid season aren’t affected because houses are well ventilated and often built off the ground.
‘Good ventilation is the main cure to damp. You should open up the house to ventilate against dampness.’
The hidden causes
Mould is a living organism that blows in from outside and is fairly harmless unless it comes into contact with moisture.
When the two combine, the dampness feeds the mould. Scott says a mould detector placed against a wall can sense if there’s a problem before it starts to show.
‘Most people think rising damp comes up the walls but in 90% of cases the moisture comes off the ground. Rising damp happens when moisture sits under a house then the sun comes out causing humidity.’
It can also provide a breeding ground for pests.
‘Structurally these conditions are a magnet for termites that feed off damp timber and cockroach infestations are also likely.’
TIP Tackle damp-prone areas of the house such as kitchens and bathrooms with specialist paints and primers designed to combat damp and mould.
Solution 1: Underfloor ventilation
For houses with an underfloor cavity, restoring and maintaining the underfloor ventilation may be enough to fix a damp problem.
Damp air is removed from under the floor using a circulation pump and replaced with fresh, dry air that is forced to move in a drying pattern through the damp air space.
The pattern is calculated based on air volume and an environmentally friendly air pump ensures the correct amount of circulation occurs.
To install in some homes, large vents about a metre apart improve the airflow sufficiently to keep the subfloor dried out.
But for situations with permanently damp soil, mechanical ventilation may be needed.
While this will cost in the thousands, it eliminates conditions where termites can flourish, so can save money in the long run.
TIP When renovating, maintain or repair a ventilated timber floor rather than replacing it with a concrete slab poured on sand or fill.