Who is responsible for fixing Mould?

Mould is a variety of fungi that grow naturally on plant and animal matter. Mould spores are fungi seeds drifting in the air until they find a spot to germinate and grow.

Mould needs food, and pretty much anything organic will do. House dust is a favourite because it has everything from skin cells, hair, clothing fibres, bacteria, dust mites, pollen and so on. And it is everywhere, which is why Mould can grow on metal window frames, for example.

Mould also much prefers to be left alone, at least until it gets established. Still air allows the spores to settle on things and take root without being disturbed. And some of the stillest air is against walls behind furniture, the backs of wardrobes, behind beds and blinds on windows that are never opened.

But most importantly, the spores need water to grow. Most commonly, they drink the humidity from the air. Certainly, water from leaks and splashes left without mopping up also helps. (Think of the Mould you get in the bathroom in tile grout and under sealing joints).

Mould is what happens when you have a moisture problem. Fix the moisture problem, and you fix the mould problem. It sounds simple, but it’s not.

How much humidity is too much?
Mould generally needs about 65% humidity or more to grow and multiply. When the humidity gets down to 50% or lower, it is too hard for it to suck water out of the air, and it stops growing.

Fun fact, the Australian Bureau of Meteorology reports the average humidity in Sydney over a typical year is 57%. Add to that water pumped into the air by clothes dryers, cooking, showering, and breathing, it does not take much to lift the humidity level in a property up over the 65% threshold. You will create the perfect environment of Mould just by living in a property unless you deliberately do things to bring that humidity down.

The more humid the conditions, the faster Mould grows. Research shows that once humidity hits 80% or more, Mould can grow at such a fast rate that it will destroy most things in just a couple of weeks. With humidity at 70%, it takes a little longer but wait three months and you will be throwing out clothes and shoes with the best of them.

Humidity vs leaks
The most common assumption is that Mould is a sure sign that there is a leak somewhere. While it is possible, most leaks cause more obvious issues like holes in ceilings, water running across the floor, and watermarks and paint peeling off walls. A good quality moisture meter can check water content of the structure to show if there is a leak. From concrete to gyprock, these meters read down to a depth of 10cm. In most instances, we find the walls with Mould have the same water content in them as those without Mould. That means the Mould is getting water from the air rather than from a leak.

Cooking, washing, showering, and drying clothes put water into the air. The average person breathes out around half a litre of water daily. As we sleep in bedrooms, we are pumping out water, and if the windows and doors are shut because we want to stay warm, the water vapour is trapped. That is why a lot of bedrooms suffer from Mould.

Contain the wet air
Of course, you must cook, do laundry, shower, and breath in your home. Reducing the amount of water being evaporated is not always possible. But you can stop that wet air from being spread around.

Keep bathroom doors closed during and after showering and laundry doors closed while drying clothes. You’ll still need to get the wet air out of these rooms, but at least the rest of the property will stay below the humidity threshold Mould needs to grow.

Condensation gives hints
Look for condensation; it is often on windows in the morning, on the walls and ceilings of laundries and bathrooms. The rooms that have condensation have a moisture problem. If you have Mould, look for condensation; if you see some, think about where the water comes from. Is it from an adjacent bathroom or a clothes dryer? Portable gas heaters put out a lot of water or never underestimate your breath as you sleep at night (we are not suggesting you shouldn’t sleep).

Be conscious of the rooms where these water pumping activities happen and think through how you might move that wet air outside.

Ventilation is as much about timing as it is about time
If you say you have mould, everyone will tell you, you just need to ventilate. And everyone with a mould problem will says they are already doing that.

Windows need to be partially open, not wide open. Please think of how draughts work; you feel them even though the gaps they come through are small. We are talking about windows being open a centimetre or two.

Ventilation also works best if there is an in and an out. If you leave a bathroom window slightly open, leave the bathroom door ajar so the air can flow out. It’s the same with the bedrooms; a gap between the bottom of the door and the floor may be enough.

The most common mistake people make ventilating is they do it when they aren’t using the room and don’t do it when they are. That’s a timing issue. If you sleep with the windows and door closed and then open the window when you leave in the morning, it is already too late. The water in the air has already condensed on walls and windows, and the Mould is happily absorbing it up and growing.

As soon as you start creating water vapour, you will probably pump water into the air faster than you can pump it outside. That means you probably need to ventilate for longer than the activity creating the water vapour. Ventilate while the room is in use and after you have finished using it. It will take a while for the humidity to drop.

Ventilation also helps keep mould spores moving around. You don’t need a hurricane blowing through the property, but you need the air to move.

Extracting humidity
Use the exhaust fans in kitchens and bathrooms and keep them running for longer than just for the period you were cooking, showering, or drying clothes. Keep the doors slightly ajar to allow air to enter and run the exhaust fan for an hour extra.
Air conditioners are great at removing water from the air. Their powerful fans move large volumes of air past their condenser coils each minute they run. Many air conditioners have a dry mode that neither cools nor heats the air but dries it, as the name implies. Drying the air takes less energy and time than using the air conditioner to heat or cool.

Dehumidifiers are just portable air conditioners without a heat or cooling function. Because they are smaller, they use less power. Because they are portable, dehumidifiers can be moved to parts of the house that air conditioning may not reach.

Some products like Damp Rid typically use Calcium Chloride, a salt that absorbs water vapour. The salt also dissolves into the water it pulls out of the air, so you will need to change/replenish the crystals every 3-4 weeks. These products will help protect the places Mould likes to grow, like your wardrobes and bedrooms.

Cleaning mould
Cleaning mould is not easy. The places it likes to grow are out of the way and hard to reach because that is where the air is still. Cleaning surfaces of Mould stops the Mould from eating into and damaging those surfaces.

If you can get control of the humidity and keep it down, the Mould will die back. Ironically that’s when the smell will be most pungent. The Mould that lacks water quickly releases its spores to float away to more humid areas. That pungent smell of Mould can be a sign you are winning. Cleaning mould removes it, so it doesn’t ‘flower’.

You can’t clean your way to being Mould free if at the same time the humidity is ‘tropical’. Mould is too tough and just to fast. When you have the air quality under control, cleaning the next Sydney wet is less likely to cause you problems.

Yes, but who is responsible
No one wants Mould. It is ugly, smells and wrecks things. If someone can fix the problem and they don’t, they are responsible.

Mould is a moisture problem. It is caused by water in the air trapped in the property. If you can move the wet air to the outside, then it’s your responsibility. As a tenant, you must modify your behaviour to contain and remove the wet air. If you are a landlord, you must ensure the property’s equipment that is capable of removing wet air does what it is supposed to do.

Finally, and this may seem harsh; if Mould is a problem in a property and it is not a structural fault, and a tenant refuses to do what they can to stop the Mould, then we recommend the lease be terminated. The relationship isn’t working. Mould is bad for the tenant and the property, and the problem will only worsen.

Conquering mould is about understanding problems and taking the right actions. Talk to us, and we will come and look, we will test and suggest. Then you decide.