How to protect your home from mould

Panorama, the investigative documentary series, recently investigated the prevalence of mould in rented properties across Britain. In an associated article, the BBC spoke to affected families and revealed that, according to the government, mould is putting the health of two million people under threat in England alone! It is widely known to cause and exacerbate conditions such as respiratory illnesses, allergies and infections, and can even trigger asthma attacks.

At Thrift, we frequently partner with organisations to improve social housing up and down the country through energy-efficiency measures such as internal and external wall insulation. Like all installers carrying out publicly funded retrofit programmes, we are required to operate in compliance with PAS 2035, a standard designed to reduce defects and unintended consequences, including – you guessed it – mould!

Correctly specified and installed insulation can help to prevent mould – but it’s hard to know what to look out for if you’re not an industry professional. In this blog post, we will highlight some of the factors that contribute to mould and related issues, showing you what to look out for – especially when working with an installation partner to improve the energy efficiency of your home.

Inadequate insulation

Mould is a fungus that germinates in damp places, which is why condensation is a major contributor to its growth. When warm air comes into contact with cold surfaces (such as uninsulated or poorly insulated walls) it turns into water droplets and the surface can become damp. In this way, inadequate insulation can lead to mould (as well as being bad news for your energy bills and carbon footprint).

Incorrectly installed insulation

Incorrectly installed insulation is a major culprit when it comes to the development of mould. We’ll address each type of insulation here, to show you where issues can occur.

1. Cavity wall insulation – when not installed correctly, cavity wall insulation can contribute to dampness inside your property. Common installation issues include incomplete filling, which creates cold spots where condensation can form, and failure to remove existing rubble from the cavity before installation. Any rubble or debris can act as a bridge for moisture, compromising the insulation and eventually causing dampness internally.
2. Loft insulation – proper ventilation is crucial when installing loft insulation. If ventilation is compromised (i.e. by blocked eaves or incorrectly installed ventilation systems) condensation can build up in your loft space. This is particularly problematic when bathroom extractor fans vent into the loft rather than outside the property, as this introduces additional moisture into an enclosed space.
3. Solid wall insulation – several pre-existing conditions need to be addressed before solid wall insulation can be effectively installed. These include checking for and treating any existing dampness, ensuring there’s an existing damp proof course that has not been bridged (i.e. moisture has not been able to bypass it), and repairing any leaking rainwater pipes or guttering that could be saturating the walls. The installation must also account for cold bridging (areas where cold can transfer through the building fabric), and any defective rendering should be repaired. Failure to address these issues before installation can lead to damp and mould problems.

Lack of ventilation

Although we have touched on this, it really is worth examining more closely. A big part of retrofitting insulation relates to the correct installation of ventilation. On publicly funded projects, this is specified by the Retrofit Co-ordinator and includes installing or upgrading mechanical ventilation in all ‘wet rooms’ (think kitchens, bathrooms and utility rooms) and background ventilation, including trickle vents on windows undercuts on doors. You can read more about why proper ventilation is integral to home insulation in this previous post.

Behavioural factors

While building issues are often to blame for mould problems, the way we live in our homes can also be a significant contributing factor. Drying clothes indoors is a prime example – something many of us do, especially during wet weather or if we don’t have outdoor space. Without adequate ventilation (such as an open window), this can release significant amounts of moisture into the air. Similarly, cooking without using extractor fans or taking hot showers without ventilation can add moisture and contribute to dampness.

Inadequate heating systems

When some rooms or areas of your home are significantly colder than others, the temperature difference creates ideal conditions for condensation to form when warm air meets cold surfaces. This is particularly problematic in properties with inefficient or outdated heating systems. The NHS recommends keeping your home heated to at least 18°C throughout winter, with consistent heating being more effective than short bursts of high temperatures and helping to prevent condensation.

Preventing mould with a comprehensive approach to retrofitting

At Thrift Energy, operating to PAS 2035 standards means we thoroughly assess the entire property’s condition before any work begins. This assessment is reviewed by an independent Retrofit Co-ordinator who makes detailed recommendations and issues an approval for works to be installed. This rigorous process helps prevent unintended consequences like mould and provides valuable protection for consumers.

If you’re planning energy efficiency improvements for your property, always look for Trustmark-registered businesses who follow PAS 2035 standards. This gives you peace of mind that your installer understands the complex relationship between insulation, ventilation and heating, and will take steps to ensure your retrofit project improves your home’s comfort and efficiency without creating new problems. After all, making your home more energy efficient should enhance your quality of life, not compromise it.

To learn more about how Thrift Energy can help you insulate your home, get in touch with our team today.

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