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What to Do When There’s Mould in Your Loft

Mould on wall

It can be alarming to find mould in your loft. There are various consequences caused by mould, ranging from structural damage to impacting air quality. It should always be addressed immediately, and steps should be taken to prevent it from happening again. Our guide will detail what to do if you find mould in your loft.

You can also view our guides on loft room conversions and loft conversion windows for more helpful information.

What causes mould in lofts?

Mould in lofts is primarily caused by excess moisture and poor ventilation. When warm air rises from the lower parts of a home and reaches the cooler surfaces of the loft, condensation occurs. This moisture provides a perfect breeding ground for mould spores that are naturally present in the air. Factors such as leaking roofs, poor loft insulation, and blocked air vents can cause this issue by trapping moist air in the loft space.

Learn more about how to stop condensation on roof lanterns.

Where does it tend to grow?

Let’s look at the main places mould tends to grow.


Mould tends to grow on wooden surfaces within lofts because wood can absorb and retain moisture. This makes it one of the most common materials in a loft to host mould growth. Regular exposure to damp conditions can lead to the deterioration of wood, which further facilitates mould infiltration and growth.

Insulation foam

Insulation foam, often used for energy efficiency in homes, can also be susceptible to mould if exposed to moisture. Because insulation materials are designed to trap heat, when they become wet, they can also trap moisture, creating an ideal environment for mould to grow. This is particularly a problem in lofts where insulation is not installed correctly, allowing moisture to accumulate.

What to do when you find mould

Discovering mould in your loft can be worrying, but addressing it as soon as possible is important to prevent further spread and structural damage. The first step is to assess the extent of the mould growth and identify the moisture sources contributing to it. Once the source is located, it can be dealt with to prevent future occurrences.

Improve ventilation

Improving ventilation is one of the most effective ways to prevent mould in the loft. This can be achieved by installing additional air vents or a mechanical ventilation system. Ensuring that existing vents are not blocked, so air can circulate freely helps reduce moisture levels, making the environment less hospitable for mould.

View our loft ventilation guide and learn more about different types of roof vents.

Improve insulation

Upgrading the insulation in your loft not only enhances energy efficiency but also helps in controlling temperatures and reducing condensation. It is important to make sure that the insulation is properly installed and covers all areas without gaps, which can lead to cold spots where condensation forms and mould grows.

Learn how to insulate your windows in our helpful guide.

Fix any leaks

Leaks from the roof or around windows can cause significant moisture into a loft space, allowing mould growth. Inspecting the loft regularly for signs of leaks and repairing any damages immediately can prevent water from seeping into the loft and contributing to mould problems.

Use a dehumidifier

Deploying a dehumidifier in your loft can significantly help reduce moisture levels, which are important for mould prevention. Dehumidifiers extract water from the air. This maintains a drier atmosphere, preventing mould growth. It’s advisable to choose a dehumidifier with a capacity appropriate for the size of your loft to ensure effective moisture control.

Add windows or skylights

Adding windows or skylights into the loft can improve both ventilation and natural light, both of which are natural deterrents for mould. Increased sunlight can help to keep the loft dry and warm, reducing the likelihood of condensation and mould growth. Additionally, windows can be opened to improve air circulation.

You can also learn when to replace a skylight if you already have one, as well as when to replace your existing windows.

Add loft vents

Installing additional loft vents is another way to improve air circulation and decrease moisture build-up. Proper placement and size of vents is important when creating an effective airflow that can sweep away moist air before it condenses on surfaces. This is particularly useful in lofts that are used for storage or have been converted into living spaces.

View our guide on the different types of roof vents.

Maintain a consistent temperature

Keeping a consistent temperature in the loft can prevent the warm air from lower floors from rising and condensing in the cooler loft space. Using thermostatic controls to manage the temperature or ensuring good thermal insulation can help maintain an even temperature, reducing the risk of condensation and mould growth.

Shop quality skylights at Toughened Glass Systems

Toughened Glass Systems has a range of high quality skylights that can offer ventilation to your rooms which can aid in preventing mould growth. Our selection includes bathroom skylights, kitchen skylights, living room skylights, bedroom skylights, pyramid skylights, aluminium skylights, and more

More helpful articles


Is it normal to get mould in a loft?

It’s quite common to find mould in lofts because they often get cold and damp. You should always deal with mould right away to avoid damage to your home and health risks.

How serious is mould in an attic?

Mould in an attic is a serious issue. It can damage the building and affect your health, especially if you have allergies or asthma.

How do you remove mould from roof joists?

To remove mould from roof joists, first make sure you wear protective gear like gloves and a mask. Clean the mould with a mixture of water and vinegar, or use a mould cleaner made for wood. Scrub the area well, then make sure it’s completely dry. If the mould is widespread, you might need to get professional help.

Based on 210 reviews
Bob toploft
Bob toploft
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Jim H
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Jack Smith
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Paul Smith
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