Home Improvement

Black Mould On Windows: Remove & Prevent In 8 Steps

Written by  Harry Taylor
Last updated: August 8, 2023

Mould removal is tricky. You can’t just wash with a random cleaning solution. If you do, you may spread the infestation to other parts of the house. Even if you manage to remove mould this way, it will probably come back, putting you, your loved ones and your property in danger again.

To successfully fight black mould, you need a cleaning solution to kill the spores and disinfect the window. You must also move quickly because black mould is a very dangerous fungus. Once it starts growing on a window, every occupant of that house, living and nonliving, is at risk.

Black mould spores can spread through the air. So, the infestation will eventually find its way to other parts of the house. It will stain and destroy every item it touches. It will also put everyone at risk of breathing and skin problems.

Fortunately, this article will show you how to remove black mould in just 8 steps. In fact, we will take it a step further by showing you how to prevent another infestation.


  • The cleaning agent: You can use vinegar, bleach or dedicated mould remover
  • Water: for rinsing and making the cleaning solution
  • A bucket: For carrying water and the cleaning solution
  • A non-abrasive brush, microfiber cloth and rag: for removing the mould by scrubbing and wiping
  • Spatula or utility knife: For scrapping off black mould spores in cracks and corners 
  • Protective clothing: eye goggles, mask, gloves and PPE gown to protect yourself and your clothes.
  • Bin bags: to control waste distribution and handle disposal  

Now that you know the supplies, here is how to remove black mould from a window in 8 steps.

Step 1: Prepare the site

Firstly, open the windows and doors that lead outdoors. You don’t want to lock yourself in an enclosed space with all those toxins and chemicals in this task.

Then, clear the site around the window. Remove the window curtains, furniture and other items in the area. You can move them to a corner or another room.

Finally, close doors that lead to other parts of the house. This will stop the mess of this task from spreading to those spaces.

Step 2: Suit up

Safety is crucial during black mould removal. So, you need to suit up. Wear the protective clothing in your supplies. By this, we mean the goggles, mask, rubber gloves and PPE gown.

Step 3: Cover the floor with bin bags

Use some of the bin bags to cover the floor around the infested window. This will control waste distribution, making the clean-up easier.

Step 4: Make the cleaning solution

If using bleach, mix one part bleach with three parts water. For vinegar, use undiluted or one-part vinegar. As for the dedicated mould remover, follow the instructions provided by the manufacturer.

Step 5: Apply the cleaning solution

If using bleach, dip the non-abrasive brush, microfiber cloth or rag into the bleach-water mix. Then use it to scrub the mould off the window. Scrub gently, almost like you are collecting or wiping off the pores. Otherwise, you could end up spreading the mould to other areas.

For vinegar, fill a spray bottle with the cleaning solution. Then spray on the affected areas and wait for one hour. After this, you can scrub with warm water.

You need to clean every part of the window panes, frame and surrounding brickwork. You can use the spatula or utility knife to scrape the spores in cracks, corners and other hard-to-reach areas.  

Step 6: Wipe with warm water

Dip a new microfiber cloth or rag in warm water. Then use it to wipe the entire window and nearby brickwork. Wipe every wear that you just treated.

Step 7: Cleanup and dispose of the wastes

Clean and disinfect the bucket, brush, utility knife, spatula and other tools used during this task. Then, collect and dispose of the rags, microfibre clothes, bin bags and other waste materials.

Step 8: Dry

Wait for the window and its surroundings to dry. Don’t close the window until dry because dampness encourages black mould infestation. It started this problem in the first place. 

How to prevent black mould on a window

To prevent black mould from growing on your window or any part of your house, you must understand what causes it. Then you can take measures to avoid those causes. As you already know, dampness cause black mould.

So, it is a sign that your window is damp, usually due to condensation and leakage. In this case, condensation happens because the room is too humid. So when moist air comes in contact with the cold glass panes of the window, it loses moisture. On the other hand, leakage happens because a structural fault allows rainwater to sneak in through the window.

Both condensation and leaks make windows damp, thus encouraging mould growth. Therefore, you must prevent condensation and leakage if you don’t want black mould on your windows. Here are some tips.

Check the window for damages and make necessary repairs

Structural problems leave windows vulnerable to condensation and leaks. The resulting dampness and black mould can also cause more damage.

So, you need to fix the damages to avoid more problems. Sometimes you may even need to replace the entire window.

Keep your windows clean

Black mould benefits from dust and organic substances that accumulate on windows. The deposits serve as mould food while also causing drainage problems and leaks. All of these create an encouraging environment or black mould. Plus, no one likes dirty windows. 

So, clean your windows as often as possible. Clean every part thoroughly, including the glass panes, frame, sill and tracks.

Install double or triple glazing

They cost more but are much more durable and resistant to condensation and leaks. They also provide superior energy efficiency and security.

Install UPVC or aluminium frames

The organic nature of a wooden window frame makes it vulnerable to black mould and dampness. In many ways, it is also less durable than aluminium and UPVC frames.

You can reduce the risks by painting or staining the wood. However, UPVC and aluminium remain better alternatives for a house with damping and black mould problems.

Aerate the house daily

Leave the windows open for about 15 to 20 minutes to let in some fresh air. Just doing this daily will have an incredible impact on the ventilation in the entire house.

Poor ventilation is the reason for high humidity and its associated problems. That is why moulding and other ventilation related-problems are more common in cold seasons.

Don’t dry clothes indoors

This will only add to the moisture levels. However, if you don’t have an option, consider limiting the activity to a single room and opening the windows. You should also close doors that lead to other parts of the house.

Get an Extractor fan or/and a dehumidifier

An extractor fan will help to remove moist air from the house, while a dehumidifier will reduce the amount of moisture in the air. Either of these will reduce dampness, thereby preventing black mould. 


When it comes to black mould removal, speed is an asset. You need to move quickly because the infested window is not the only thing at risk; everything and everyone is too. However, black mould removal is also a dangerous task. Anyone involved is exposed to mould spores and hazardous chemicals.

That’s why you should open the windows and wear protective clothing. However, no matter the protection, it is not a task for someone with respiratory issues.

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