How to get rid of mould on window sealant

Knowing how to get rid of mould on window sealant can quickly improve the appearance of your home. Even a small amount of mould can make a room feel cold, damp and uncared for, so tackling it early makes a big difference.

What causes mould on window sealant and around windows?

Black mould around windows is not only unpleasant to look at — it can also produce a damp, musty smell and spread across paint, wallpaper and plaster. If left untreated, it can even contribute to respiratory issues, especially for those with asthma or allergies.

It’s important not to ignore even the slightest sign of black mould around your windows, or anywhere else in the home.

There are two main causes of black mould around windows:

1. Leaks

If water is getting in from outside, the sealant may need repairing or replacing. No amount of cleaning will fix mould caused by an active leak.

2. Condensation

This is the most common cause — and the good news is that it can be treated and prevented with the right steps.

How to reduce mould caused by condensation

There are a few things you can do to help reduce the amount of mould that appears due to condensation. Here are six things that will help.

• If you have single-pane windows, replace them with newer double or triple-glazing which are far more mould resistant.

• Keep the window vent (trickle vent), found at the top of windows to let in air from the outside, open to ensure maximum ventilation throughout the home.

• Add or use extractor fans when cooking in the kitchen and washing in the bathroom to remove excess moisture present in these rooms.

• Purchase a portable dehumidifier which will extract moisture from the air - bear in mind these can use a lot of electricity model dependant.

• Open up your windows to keep your home well ventilated – only when it's not too cold to do so though!

• Move houseplants away from the windows - they actually moisture into the air, and if too close to windows will add to the problem.

The most common cause is a lack of ventilation. Rooms without sufficient ventilation after a shower result in mould being a common sight. Simple steps as detailed above can help make this issue a thing of the past.

Can you remove mould from window sealant?

Yes — but the sooner you tackle it, the easier it is to remove. Here are the key steps:

1. Apply a paste of white vinegar and baking soda to the mouldy areas.
2. Scrub stubborn stains with a stiff‑bristled brush or reapply the paste.
3. Rinse with a cold, damp sponge and dry with a microfibre cloth.
4. Use a bleach and water spray on bathroom sealant to kill mould spores.
5. Ventilate the room well and clean regularly to prevent mould returning.

If mould has been left too long, the sealant may be permanently stained or damaged. In that case, you may need to remove the old sealant and reseal the area. This is why reducing condensation is so important — prevention is always easier than cure.

When should you replace the sealant instead of cleaning it?

Cleaning works well for light to moderate mould, but replacement is usually needed if:

• The sealant has turned orange, brown or black permanently
• The mould has spread behind the sealant
• The sealant is cracked, peeling or lifting
• The mould returns within days of cleaning
• The sealant feels soft or crumbly

Replacing sealant is a straightforward DIY job for most people and often gives the best long‑term result.

How to prevent mould returning after cleaning

Once you’ve removed the mould, keeping it away is the next step. Here are simple habits that help:

• Wipe condensation from windows each morning
• Keep blinds or curtains slightly open to allow airflow
• Avoid drying clothes indoors where possible
• Leave bathroom doors open after showering
• Use mould‑resistant sealant when resealing
• Keep extractor fans running for 10–15 minutes after use

Small daily habits can make a big difference in preventing mould from returning.

In summary

We hope you’ve found this guide on how to get rid of mould on window sealant useful. If tackled early, mould is much easier to remove and far less likely to cause long‑term damage. Following the simple steps to reduce condensation will also help prevent it from coming back.

Green Fox Cleaning are a commercial cleaning company operating across all sectors. Click here to learn more about us, and discover how we can help improve the appearance of your business.