According to EXPRESS

Mould growth around windows is a common household problem, particularly during colder seasons when condensation builds up on glass and frames. Recent reporting highlights that while window mould is often treated as a cleaning issue, it is more accurately a symptom of excess indoor moisture combined with insufficient ventilation.

Experts stress that without addressing the underlying environmental conditions, mould around windows is likely to return, regardless of how often it is cleaned.

Why Window Mould Develops

Window mould typically forms when warm, moisture-laden indoor air comes into contact with cold window surfaces. As the air cools, water vapor condenses on glass, frames, and surrounding seals. This persistent dampness creates ideal conditions for mould spores to germinate and grow.

Modern homes, which are often better insulated and more airtight, can be particularly vulnerable. While improved insulation reduces heat loss, it can also trap moisture indoors if ventilation is inadequate.

Common contributors to window mould include:

daily activities such as cooking and showering
drying clothes indoors
limited airflow during colder weather
poorly insulated or single-glazed windows

Over time, moisture accumulation becomes concentrated at window edges, where mould frequently appears.

Health and Indoor Air Quality Concerns

Although window mould is often localized, it can affect indoor air quality. Mould releases spores and microbial volatile organic compounds into the air, which may irritate the respiratory system.

People most vulnerable to mould exposure include:

individuals with asthma or allergies
young children and infants
older adults
people with weakened immune systems

While small patches of mould are unlikely to cause severe illness in healthy adults, experts recommend prompt removal to reduce prolonged exposure.

Cleaning Methods Highlighted by Experts

The report emphasizes that window mould on hard, non-porous surfaces can often be removed using simple household solutions when addressed early.

One commonly recommended method involves using white vinegar, which has mild antifungal properties. Vinegar is applied directly to the affected area, left to act for a short period, and then wiped away with a clean cloth. This approach is intended for light to moderate mould growth on window frames and seals.

In some cases, warm soapy water may be used to remove surface dirt before applying vinegar. Experts caution against mixing vinegar with other cleaning products, particularly bleach, due to the risk of producing harmful fumes.

Limitations of Surface Cleaning

Specialists consistently note that surface cleaning alone does not solve mould problems. While vinegar or detergent may remove visible growth, mould hyphae can remain embedded in surrounding materials if moisture persists.

Additionally, cleaning does not address condensation, which is the primary driver of window mould. Without changes to ventilation and humidity control, mould is likely to reappear.

Experts emphasize that repeated cleaning without prevention may give a false sense of resolution.

Prevention Through Moisture Management

Preventing window mould requires reducing indoor humidity levels and improving airflow, particularly near windows.

Recommended preventive measures include:

wiping condensation from windows daily
opening windows briefly to allow moisture to escape
using extractor fans during cooking and bathing
maintaining consistent indoor heating
using dehumidifiers in moisture-prone rooms

Improving window insulation can also help by keeping surfaces warmer and reducing condensation formation.

Ventilation as a Long-Term Solution

Ventilation is repeatedly identified as the most important factor in preventing window mould. When moist air is allowed to circulate and escape, condensation is less likely to form.

Experts advise that even during cold weather, short periods of ventilation can significantly reduce moisture buildup without causing major heat loss.

In properties with persistent mould issues, mechanical ventilation systems may be necessary to maintain healthy indoor humidity levels.

Why Window Mould Often Returns in Winter

Window mould tends to worsen during winter because homes are closed up to retain heat. Reduced ventilation, combined with increased indoor moisture from daily activities, creates a seasonal spike in condensation.

Cold outdoor temperatures also make window surfaces colder, increasing the likelihood of moisture forming on frames and seals.

Experts note that this seasonal pattern can mislead homeowners into thinking the mould is weather-related rather than a controllable indoor issue.

Common Mould Species Found Around Windows

Window mould is most commonly caused by fungi that thrive in damp indoor environments. These include:

When Professional Help Is Needed

If mould around windows is extensive, spreading beyond frames, or accompanied by musty odors throughout the room, professional assessment may be necessary.

Persistent mould may indicate hidden moisture problems, such as:

water ingress around window seals
thermal bridging
structural damp

In such cases, addressing the building fabric is essential to prevent ongoing growth.

Conclusion

Window mould is a visible sign of excess indoor moisture rather than a simple cleaning problem. While household cleaning methods such as vinegar can remove surface growth, long-term prevention depends on controlling condensation through ventilation, heating, and humidity management.

Experts emphasize that understanding why mould forms is key to stopping it from returning. Treating the environment, not just the surface, remains the most effective strategy for maintaining healthy windows and indoor air quality.