6 ways to reduce black mould around windows

9 ways to reduce black mould around windows
Frustrated by black mould and condensation on your windows? Follow our 9 top tips to reduce black mould around windows.

If you have black mould around windows your first priority should be to get rid of it before it spreads. 

Black mould has been shown to be harmful to health and the NHS state that if you have black mould in your home you are more likely to have respiratory problems, respiratory infections, allergies or asthma.  

If a home does not have a continuous supply of fresh air into it the relative humidity rises, and the internal atmosphere quickly becomes full of airborne moisture. Eventually this build up of water in the air leads to condensation forming on the colder surfaces of a property including windows, corners of rooms and cold walls.  This condensation moisture is pure water which mould just loves to grow on!

Blcak mould will continue to grow and spread until it is killed and removed from around the windows. For small jobs this removal can be carried out by the homeowner, however, for anything larger than a dinner plate sized patch of mould you are strongly advised to get professional mould removal carried out.

How to clean black mould from around windows

Mould on window frames is one of the common places to find mould in a home. This is because the windows are relatively cold compared to rest of the room leading to any condensation forming on the window pane. Water running down window glass is a very common sight in bedrooms first thing in the morning.

The mould will typically be found on the frame around the glass and it seems to love the rubber seals around uPVC. It is important to note that on uPVC the mould cannot really damage the window but of course it can cause health problems for the occupants. If you have wooden window frames then extra care should be taken as some types of mould will feed on the wood causing damage to the frame.

When removing mold from your windows, it is important to understand that safety comes first, you don’t want to spread the mould spores around the house even more.

  • Before you begin,  put on a dust mask. You want to make sure you do not breathe in the dangerous spores that the mold can release into the air. The mask may also help protect you from inhaling cleaning chemicals.
  • Cover the floor under the window you’re cleaning to catch any of the falling mould which can be disposed of later.
  • Make sure there is adequate ventilation in the room. Open a window or door so the mould spores can escape.
  • Do not use bleach as this only removes stains but does kill mould! Use a commercial mould killer or the Ultimate Mould Killer from Ministry of Mould. Scrub the mold off of the windowsill using a non-abrasive brush and frequently dip the brush in the bleach mixture. Use a clean rag to then wipe away the mold you loosened. It can be hard to get right into the cracks, particularly with uPVC, but try a stiff brush for these areas or even scrape the mould out with a butter knife. 
  • Allow the windowsill to dry completely before you close the window. Wipe off any remaining residue.


One of the more recent developments for treating mould around windows is to invest in a Karcher Window Vac which effectively sucks away the water droplets on the window. Using the window vac every morning will help to keep the amount of mould around windows down to a manageable level. 

How to stop black mould long term

Cleaning off the mould in one area can work in the short term. Longer term it is likely to lead to an endless cycle of cleaning and redecorating. 

Below are 9 tips for stopping black mould long term. Some are easy to do and can be actioned right away, while others need more investment and professional help. 

Open a window!

Yes, this one is so simple that is goes top of the list. The most common place for black mould around the windows is in the bedroom. Why? Because each adult sweats and breathes out an incredible 2 pints of water each night! 

The snag is that this water has to go somewhere, so if floats around the room in the air and condenses out on the cold window frames. Unfortunately, black mould loves to grow on this pure water and so it doesn’t take long for the mould to start growing. 

Opening the window increases air changes in the room which brings down the amount of water vapour in the air. Even if you live in a town, windows can often be left open a crack and still be secure. 

condensation on window

Shut the door!

Second on the list isto shut your bathroom door after showering. This one is really simple but so often overlooked by many people. 

Steam is created when you bath or shower and you want that steam to go anywhere but back into your house. So shut the door to the bathroom and stop the condensation on the windows in your house. 

shower door bathroom black mould

Warm up the walls!

To some extent it is impossible to stop all moisture in the air which causes black mould around the windows. I mean, you have to breathe and this makes moisture. 

So the next tip is a good one – warm up the walls around the window and the window reveals to stop condensation forming. If you stop the condensation you will stop the mould growing. 

We sell a thermal paint called Mould Be Gone which warms the wall by a small amount, just enough to stop condensation forming. 

Dry clothes safely!

If you are a tenant then your landlord may have said not to dry clothes on the radiator as they release loads of water into the air. They are correct, but sometimes this is not always easy, I mean you have to dry clothes somewhere right?

The best thing is to dry clothes in one room only using a clothes drying rack. Make sure that the window is left open and the door is firmly kept shut. If you have a dehumidifier then running that with window shut will also work well. This keeps all the moisture in the one room and does not let it float around to cause mould on your windows.

clothes drying inside

Improve ventilation!

The absolute hands down best system for stopping condensation forming and therefore mould forming around windows is to install a PIV system.

These amazing units work by trickling fresh air into the property continually, which brings the humidity down and keeps condensation away. They work very very well and are trusted by social housing providers across the UK.

For a PIV quote take a look at our PIV page here.

how does a piv system work to stop black mould on windows

Keep your home tidy!

At the risk of patronising you – a clean and tidy home is less likely to have mould problems. Piled up clothes, furniture, boxes etc all cause air flow to be reduced with the result that condensation is more likely to occur in corners of rooms and behind things.

If you have a cluttered home and a mould problem, then now is the time to have a clear out and donate to charity.

messy home causes mould problems


Hopefully, that quick bit of info will help you live mould free. Remeber the key is to keep humidity and condensation levels as low as possible. Sometimes this can’t be achieved without outside help – if you find that you struggling then contact us for help. 

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