How To Prevent Mould In Your House In Winter

Winter provides the perfect conditions for mould to proliferate indoors, and preventing it can be far easier than treating mould after it’s appeared. As mould spores are invisible, it can sometimes go unnoticed in the early stages, but it’s critical to stop the spread as soon as possible. Mould can be dangerous to your family’s health, causing itching, rashes, asthma attacks and even long-term health problems. 

What you do before and during winter will significantly impact mould growth and how difficult it is to remove. By making a few changes around the house, you can make your home less friendly for mould spores and keep your family safe from this hidden menace. 

What Causes Mould To Grow In A House During Winter?

It’s easy to assume that mould isn’t a problem in winter, since cold temperatures make mould spores dormant. However, the reality is that winter is prime time for mould growth!

The difference between the warm indoor temperatures and the chilly air outside is what causes the mould to breed and grow. This is only worsened by people opening and closing the main door. The constant fluctuation in temperature causes condensation, and in turn, creates inviting conditions for mould.

Mould is a fungus that thrives when there are four key ingredients: oxygen, moisture, warm temperatures, and food. Mould spores feed on cellulose (found in paper, wood, cardboard, and drywall) and organic matter (found in textiles and dust containing skin cells). With all these things found in the home, mould has plenty of fuel for growth. 

Moisture is a problem in the home during winter due to: 

  • Condensation
  • Frequent rain and snow
  • Human and animal breath 
  • Steam from kitchens and bathrooms 
  • Laundry hung to dry indoors 

With houses closed up to beat the chill, homes have little ventilation that could help to dry out moisture. And given that most people use some form of indoor heating, the warm indoor temperatures are the final ingredient mould needs to thrive. 

What can we do to prevent mould in winter? Here are our top five tips. 


Tip #1: Address Leaks and Spills Quickly 

Because moisture helps mould grow, it’s important to address leaks and spills with urgency. One common cause of mould issues is undetected leaks, both in plumbing and in the roof itself. 

Stay vigilant for any signs of damp during winter, including in cupboards, behind walls and in the roof cavity. Musty smells, stains and mould growth all indicate that something might be leaking. 

If you have broken pipes or a leak in your ceiling, it’s crucial that you fix the problem immediately. Don’t wait for it to worsen, as this provides an opportunity for dangerous moulds to grow. Be sure to thoroughly dry out any leaks or spills immediately, even in tricky areas. 

Tip #2: Maximise Ventilation In Every Room 

Good aeration is vital to avoid damp pockets that invite mould spores. It may not be ideal in winter, but to maximise ventilation, you’ll need to open doors and windows. Remember to let air in and out – for instance, opening the bedroom window but keeping the door closed isn’t enough to properly ventilate the room. The air must have an entry point and an exit point.

Ideally, you should have ventilation fans installed at home, especially in the bathroom and the kitchen. Keep your ventilation fans on even after you shower or use the kitchen, as humidity still lingers in the room afterwards. An extractor fan will keep moisture from building up in the walls and ceiling. 

You can also run your ceiling fans in reverse during winter because hot air rises. The clockwise rotation can help pull warm air up and spread it from the ceiling to the walls, effectively insulating your home.

Take steps to allow good air circulation. For instance, allowing gaps between your furniture and the walls is a good start, especially in rooms that are more prone to mould growth.

Tip #3: Prevent Condensation With Insulation 

Insulation eliminates sharp temperature contrasts to prevent condensation and, in turn, mould development.

First, where possible, make sure your home is insulated. Most forms of insulation are suitable, though cellulose is best avoided as mould uses this as a food source. 

Another way to insulate your home is through your windows. You can invest in double glazed windows, which contain insulating gas, retaining warmth while minimising condensation. Perspex or plexiglass is another good option to insulate windows, although many people use bubble wrap and swear by it! 

Regardless, if your window frame is made of aluminium, you’ll need to cover it, because aluminium gets cold and attracts moisture in the winter.

While they do keep you warmer, curtains aren’t effective insulation for your windows, as they only create a pocket for mould growth. They aren’t effective at minimising condensation, so don’t rely on curtains to protect your home in winter. 

Tip #4: Reduce Humidity In Your Home 

Humidity is one of the main contributors to mould growth. If you have a humidity testing device, aim to keep indoor humidity below 50% to prevent mould from settling in. 

One source of moisture is in the kitchen, when cooking and boiling the kettle leads to steam production. This is especially problematic if you don’t have a rangehood or extractor fan, or if it vents into the ceiling cavity rather than outdoors. 


Many people also dry their laundry inside during the winter months. Just one load of washing can release two litres of moisture into the air as it dries, and this creates a damp environment that invites mould spores. Instead, consider investing in a tumble dryer that vents outside, or install an exhaust fan in your laundry. 


You can also use a dehumidifier to help indoors. In addition, some air conditioners have a ‘dry’ or ‘dehumidify’ mode. However, dehumidifiers are a last resort when dealing with mould problems, since prevention is better than a cure. If you can modify your home and your habits to reduce moisture in the air, it’s the most reliable long-term solution.

Tip #5: Kill Mould Quickly And Effectively 

Bleach and anti-mould products (including paint) unfortunately aren’t enough to solve a mould problem. Mould spores are invisible to the human eye, so it’s essential to stop the growth before it starts. By the time you see mould, it’s often impossible to get rid of using DIY methods. 

The best thing to do once you detect mould at home is to call for professional mould removal and cleaning. It’s time to intervene as soon you see water stains, peeling paint or notice a musty smell. Once you notice mould itself, it’s time to contact a hazardous material removalist.

Jim’s Hazardous Material Removal can not only remove visible mould but help address the causes, keeping your home mould-free in the long term. In addition, they work with Jim’s Building Inspections so that you can get a professional diagnosis of your mould problem.

To tackle your mould issue fast, call Jim’s Hazardous Material Removal on 131 546.