Why does mould appear?

2 hours ago

2 min read

As the colder months approach, so does mould season. With temperatures dropping, windows staying closed for longer and indoor heating becoming more common, condensation and excess moisture can quickly build up. These conditions create the perfect environment for mould to develop, particularly in areas with poor ventilation. Understanding why mould becomes more common during autumn and winter, and knowing how to prevent it, can help protect your property and maintain a healthier indoor environment.

What is mould?

Mould is a type of fungus that decomposes dead organic matter and typically thrives in damp, humid environments. Mould can appear in a variety of colours, including black, green, white and grey, depending on the type and the surface it grows on.

Mould-stained white wall with water damage above a wooden baseboard and cracked concrete floor

Although mould plays an important role in the natural environment by breaking down organic materials, its presence indoors can cause damage to walls, ceilings, furniture and other household surfaces. It can also contribute to musty odours and may trigger allergies, irritation or respiratory symptoms in some people.

When does mould appear?

Excess moisture areas
Damp surfaces and persistent moisture create the conditions mould needs to grow. Leaking pipes, damaged roofs, plumbing issues and water ingress can all introduce excess moisture into a building.
Areas with poor ventilation
Limited airflow allows moisture to remain in the air and settle on surfaces. Rooms such as bathrooms, kitchens and utility rooms are particularly vulnerable because everyday activities, including showering, cooking and drying clothes indoors, release moisture into the air.
After temperature changes
Cold surfaces can increase condensation, particularly during the colder months. When warm, moisture-filled air comes into contact with colder surfaces, such as windows, external walls and corners of rooms, water droplets can form. If condensation occurs regularly and surfaces do not have enough time to dry, mould can begin to grow.

How can mould growth be prevented?

Improve ventilation: Use extractor fans in kitchens and bathrooms, open windows when practical and ensure ventilation systems are working effectively.
Control condensation: Wipe away excess condensation from windows and other surfaces, particularly during colder weather.
Maintain a consistent temperature: Avoid allowing rooms to become excessively cold, as cold surfaces can encourage condensation to form.
Address leaks promptly: Repair leaking pipes, damaged seals, roof defects and other sources of water ingress as soon as possible.

If you are noticing persistent mould appearing in your building and would like some advice please email our Technical team at technical.enquiries@cleenol.co.uk.

Written by Neve