Top Tips on How to Get Rid of Mouldy Window Sealant & Frames

How to get rid of mould and excess moisture on window sealant

Damp, mould and condensation around window sealants and window frames isn’t just an eyesore, it’s a serious health hazard. Studies indicate that living in mould-infested environments can significantly affect respiratory health, increasing the chance of conditions like asthma and allergies – an average £38 million per year is spent by the NHS on treating patients with damp and mould related illnesses. For homeowners, landlords, tenants, and property managers, understanding and addressing the presence of window mould is crucial not only for the aesthetic appeal of your home but, more importantly, for the health and wellbeing of occupants.

In this guide, we outline typical mould species you may find around UPVC window sealant, ways to prevent mould growth and a window frame and why it’s important to limit the amount of mould surrounding your window sills.


  • Common window sealant mould species
  • Understanding the causes of mould around window frames
  • Ways to remove mould from around windows
  • Effective strategies for permanent window sealant mould removal
  • Why it’s important to get limit mould growth around UPVC sealant
  • Getting rid of window sealant mould for good

Common window sealant mould species

Mould around UPVC window sealants typically manifests as unsightly black or green patches. The most common culprit is Cladosporium, a black mould that is found in cool, damp areas. Another frequent type of mould found around window frames is Aspergillus, varying in colour from green to black and found in more humid conditions.

Recognising these specific mould species is the first step towards effective removal and prevention.

Understanding the causes of mould around window frames

Mould growth around windows can be related to condensation (not always!), which occurs when moist, warm air inside your home meets the cooler surface of the window glass, leading to water droplets that create an ideal environment for mould. Of approximately 5000 damp, condensation and mould related surveys undertaken by Cornerstone, our data indicates 91% of root causes are aligned to managing atmospheric moisture levels, rather than structural issues.

Poor ventilation

Poor ventilation traps warm air indoors, increasing humidity and leading to mould growth. Ensuring adequate airflow is crucial to prevent mould by reducing indoor moisture levels near your window frames.

Leaking windows

Leaking windows allow water inside due to faulty sealants or frames, creating a moist environment – ideal for mould growth. Detecting and addressing leaks is essential for mould prevention especially near window frames.

High humidity

Activities like cooking, showering and drying without adequate ventilation can increase indoor humidity levels – for example, drying clothes can produce between 4.0 – 5.0 litres of atmospheric moisture and activities such as breathing, generates more water vapour than a wet structure.

Ways to remove mould from around windows

While removing visible mould can improve the appearance of your window sealants and frames, it’s crucial to understand that this doesn’t tackle the underlying mycelium roots – as a result, even if the sealant looks clean, these roots persist and will likely lead to mould regrowth.

Given this, we don’t recommend just ‘cleaning’ the black mould around your wooden window frames as it doesn’t address the core issue. Using typical ‘cleaning’ solutions such as a damp cloth, scrubbing brush, bleach, washing up liquid, baking soda and white vinegar will not stop mould from growing back, it merely removes poor appearance.

To effectively and permanently eliminate mould from your window sealant, continue reading for some DIY methods, or consider consulting with one of our mould experts for specialised advice.

Effective strategies for permanent window sealant mould removal

As mentioned above, cleaning mould is a temporary fix and if you don’t address the root cause of finding black mould around windows, it will simply return. To avoid mould on windows and the surrounding sealant, you may want to consider the following DIY tips – if these don’t help, get in touch with damp and mould investigative specialist.

Improve ventilation

Regularly opening windows, the use of a window vent and using exhaust fans can significantly reduce indoor humidity and ensure maximum ventilation.

Use a dehumidifier

Maintaining indoor humidity below 60% can help deter mould growth and the ability to retain moisture. It will also improve the air quality of your bedroom, bathroom, kitchen or any other room in your property.

Fix leaks

Ensure windows are properly sealed to prevent water ingress – single pane windows are more common to suffer from leakages and the ability to release moisture on to its surrounding frame.

Regular cleaning

Keeping window areas clean and dry, limits mould exposure and formation from occurring. Having a poor ventilation system on your window sill, can cause condensation to build up and making it the perfect breeding ground for mould to quickly spread.

Why it’s important to get limit mould growth around UPVC sealant

Even the slightest sign of mould around windows is detrimental to both the health of the occupants and the structure’s appearance. Mould spores can cause serious health problems such as respiratory issues and allergic reactions, making it especially harmful in bedrooms where people spend a significant amount of time – moreover, the visual aspect of mould can decrease property value and aesthetic appeal.

Damp, condensation and mould are one of the largest collective issues facing both landlords and tenants such that, with a prevailing situation year on year, efforts to achieve long-term quality of living improvements must be at the heart of change. Mix this in with the statistic that 58% of privately rented households in England are dealing with damp, mould, and/or excessive cold in their homes, equating to approximately 2.7 million households, there is an urgent need to limit the growth of mould in all aspects, not just around UPVC and wooden windows. We have also created guides for mould on walls, mould on ceilings and mould on curtains.

Getting rid of window sealant mould for good

For those unsure how to effectively tackle mould growth around window seals and frames, seeking professional advice and services can speed up the process. An expert team can assess the situation, identify the root causes, and provide tailored solutions that not only remove existing mould but also prevent its recurrence. With the right approach, homeowners, landlords, tenants, and property managers can ensure living spaces remain healthy, safe, and visually appealing.

Remember, the key to effective mould management is not just removal but prevention, ensuring your indoor environment remains pleasant and safe for everyone.

About the Author

David Bly

David Bly

Managing Director

David has an Engineering and Management background having been involved with the property damage management industry sector for the last 20 years encompassing the management and dissemination of key reporting protocols. His field-based experience aligns to the creation and production of unique reporting systems that serve to uphold professionalism and transparency of data interpretation for the industries Cornerstone serve.

In addition, his experience aligns to the understanding of damp, condensation and mould related issues in properties combining all industry approved surveying techniques to deliver a bespoke service clients demand.

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