How to Stop Mould on Windows

If you’ve noticed black spots forming around your window frames or a musty smell in the air, you might be dealing with mould. It’s a common problem, especially in homes with poor ventilation, high humidity, or condensation issues. When warm air inside your home comes into contact with cold surfaces, it results in condensation. Left untreated, mould can damage your property and impact your health. However, with a few simple changes and some preventative care, you can stop mould from growing on your windows, and keep it gone for good. In this blog, we’ll walk through why mould appears on windows, how to clean it safely, and the best strategies to prevent it from coming back.

What Causes Mould on Windows?

Mould needs three things to thrive: moisture, warmth, and organic material to feed on. Your windows, especially in winter, offer all three. Here’s why:

• Condensation: Warm indoor air meets the colder surfaces of your window glass, turning into water droplets.
• Poor ventilation: Without proper airflow, moist air lingers, increasing humidity, which can lead to mould growing.
• Organic material: Dust, dirt, even paint or wooden window frames can feed mould.

If you live in a humid climate or keep your windows shut for long periods, the chances of mould forming increase significantly.

High relative humidity levels contribute to condensation and create an ideal breeding ground for mould and dust mites, which can aggravate respiratory issues and allergic reactions.

Is Mould Dangerous?

Yes, especially if left untreated. Black mould is particularly concerning. It releases dangerous spores into the air, which can cause health problems such as allergic reactions, asthma attacks, respiratory issues, and skin irritation. Children, the elderly, and people with compromised immune systems are most at risk. Addressing mould should be the first priority for homeowners to prevent health risks and further spread.

So while a small patch of mould might seem like a minor annoyance, it’s important to take it seriously. In a house, proper ventilation and environmental control are crucial to prevent mould growing. Neglecting these can lead to significant structural damage and health issues for the occupants.

How to Clean Mould from Windows

Before you start cleaning:

• Wear rubber gloves and a dust mask
• Open windows for ventilation
• Avoid dry brushing or vacuuming mould, as this spreads mould spores through the air
• Use a clean rag to wipe away mould after applying cleaning solutions

When removing mould, always take safety precautions seriously. Mould around window frames is common due to condensation from temperature differences. Using tools like a Karcher Window Vac can help manage and reduce condensation effectively.

What You’ll Need:

• White vinegar or a mould cleaner
• Warm water
• Microfibre cloths or paper towels
• A spray bottle
• A soft brush or old toothbrush
• Baking soda (optional)
• A dehumidifier, extractor fan, or fan (optional)

Cleaning Process:

1. Spray Vinegar or Cleaner: Fill a spray bottle with white vinegar and spray it directly on the mouldy area. Vinegar is acidic and kills about 82% of mould species. Using vinegar helps control mould by reducing moisture levels and preventing its growth.
2. Let Dry Completely: Allow the vinegar to sit for at least 30–60 minutes. This gives it time to break down the mould.
3. Scrub Gently: Use a soft brush or cloth to scrub the area. Be thorough, especially around seals and corners where mould loves to hide.
4. Rinse and Dry: Wipe the area with a clean cloth dipped in warm water. Then dry the surface completely using a separate cloth or paper towel. Mould thrives in moisture, don’t leave it damp.
5. Optional: Baking Soda Boost: Mix a tablespoon of baking soda with water in a spray bottle. Spray the area and wipe again. Baking soda not only kills mould but also helps remove odours.

How to Prevent Mould on Windows

Now that you’ve removed the mould, how do you make sure it doesn’t return? Prevention is all about controlling moisture and improving airflow. Without proper ventilation, the internal atmosphere quickly becomes saturated with moisture, leading to condensation and mould. It’s also important to close the bathroom door after showering to prevent steam from spreading. Mould around windows is a common issue, especially in older properties, and can be prevented with proper moisture control.

1. Reduce Indoor Humidity

• Use a dehumidifier, especially in bedrooms, bathrooms, or kitchens.
• Open windows regularly to let moist air escape.
• Install extractor fans in bathrooms and kitchens, and use them!
• Avoid drying washing indoors, or if you must, do so near an open window or with a dehumidifier running.

Aim to keep indoor humidity levels between 40–60%. When relative humidity rises, it can lead to moisture accumulation and condensation on cold surfaces, creating a breeding ground for mould.

2. Combat Condensation

• Wipe down windows every morning if you see water droplets.
• Use window insulation kits in winter to reduce cold surfaces.
• Consider double glazing or thermal curtains to maintain warmer glass surfaces.
• Keep blinds or curtains open during the day so windows get some airflow.
• Maintain an optimal temperature to prevent condensation and mould.

3. Improve Air Circulation

• Leave internal doors open to improve air movement within the room.
• Don’t block trickle vents or radiators.
• Use ceiling fans or desk fans in areas with poor ventilation.
• Move furniture away from walls to prevent trapped air.
• Position furniture away from external walls to prevent cold air from affecting the indoor temperature.

4. Keep Window Frames Clean

• Dust and clean your window cills weekly.
• Use vinegar or antibacterial spray to wipe down windows.
• Check for signs of cracked paint or broken seals, these can trap moisture.
• Wash your hands thoroughly after cleaning mould to prevent potential health risks.

5. Fix Leaks Quickly

If water is getting in from the outside, due to a leaky roof, broken gutter, or faulty sealant, fix it ASAP. Persistent leaks will make any mould battle an uphill one. It’s crucial to get rid of mould effectively to prevent it from spreading and causing health issues.

When to Call a Professional

If the mould keeps coming back, covers a large area, or is causing health symptoms, it’s time to call in the professionals. In a house, severe mould issues can arise due to poor ventilation and environmental control, impacting both the structure and the health of occupants.

Mould on windows is frustrating, but totally fixable. The key is consistency: clean it thoroughly, keep the area dry, and improve your home’s airflow. A little daily effort, like wiping down condensation or using a dehumidifier, can go a long way in keeping your windows mould-free. Preventing mould growing in the house is crucial, as it can lead to structural damage and health issues for occupants.

Here at UK Doors Online, we offer a range of high quality aluminium and uPVC windows, with an option of double or triple glazed windows. We also offer an optional extra of trickle vents to allow extra ventilation if desired. For more information, contact us on 01924 929 600. Alternatively, check out our online design option below to customise your windows.

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