It is widely recognised that living conditions have a significant impact on individuals’ health.
One of the most prevalent causes of unhealthy living conditions is mould and damp which can be a contributor to:
- respiratory infections and problems;
- allergies;
- asthma;
- damage to individuals’ immune systems.
Certain individuals are more vulnerable to these health issues, including babies and young children, the elderly, people with existing skin problems (e.g., eczema), those with existing allergies, asthma or respiratory problems, and individuals with compromised immune systems.
Given these risks, treating any mould and damp in your property should be a priority.
Further reading: Understanding and addressing the health risks of damp and mould in the home (Gov.uk)
Landlord responsibilities
If mould and damp are present in rental accommodation, landlords are typically responsible for addressing the issue.
According to Citizens Advice, landlords must ensure that the property remains a fit place to live, which includes addressing problems with damp and mould. Tenants should report such issues promptly, as landlords are usually only obligated to make repairs once they are aware of the problem.
What causes mould, damp and condensation in the UK?
Mould, damp and condensation are common issues in homes across the UK. Our temperate, often wet climate and the mix of older housing stock can make British properties particularly vulnerable. But what exactly causes these problems – and how are they linked?
Condensation: the most common culprit
Condensation is the most widespread cause of damp and mould in UK homes. It occurs when warm, moisture-laden air meets a colder surface – like a window, wall, or mirror – and the moisture in the air turns into water droplets.
This moisture can be generated from everyday activities such as:
- cooking and boiling kettles;
- showering and bathing;
- drying clothes indoors;
- breathing (especially in bedrooms overnight).
Condensation tends to be worse in the winter, when windows are shut and surfaces inside the home are colder. If not properly managed, this moisture can settle on surfaces and create the perfect conditions for mould to grow.
What causes damp?
While condensation is a type of damp, there are other forms too. Damp is essentially any unwanted moisture in a property, and it usually falls into three main categories:
1. Condensation damp
As mentioned, this is caused by excess moisture in the air settling on cold surfaces. It’s the most common type of damp in UK homes and is often mistaken for other forms.
2. Penetrating damp
This is caused by water getting into the home from the outside. Typical reasons include:
- leaking roofs or gutters;
- cracks in walls or broken render;
- faulty seals around doors and windows.
Penetrating damp usually shows up as damp patches on walls or ceilings, particularly after heavy rain.
3. Rising damp
This occurs when groundwater travels upwards through walls or floors, usually due to a missing or damaged damp-proof course (DPC). It’s more likely in older properties and is often characterised by tide marks and salt deposits on lower walls.
What causes mould?
Mould is a type of fungus that thrives in damp, poorly ventilated environments. It feeds off moisture and organic material (like wallpaper, wood, or fabric), and once it takes hold, it can spread quickly.
Mould often appears as black, green, or brown spots on walls, ceilings, around windows, or behind furniture. The most common type in UK homes is black spot mould.
The main causes of mould are:
- persistent condensation – the biggest trigger;
- high humidity and poor airflow;
- leaks and water ingress;
- cold, unheated rooms that allow moisture to settle.
Why it’s such a problem in the UK
Several factors make UK homes more prone to mould, damp and condensation:
- Cool, damp climate: High rainfall and long winters increase indoor humidity.
- Old housing stock: Many British homes lack modern insulation or ventilation systems.
- Energy costs: People may avoid using heating or opening windows to save on bills, which increases moisture build-up.
- Lifestyle: Everyday life creates moisture – especially in households with lots of occupants or limited space.
Treating and preventing mould
Superficial treatments, such as sprays or redecorating, may mask the symptoms but do not address the underlying issues. Effective treatment involves tackling the root causes:
- Ventilation: Improving airflow can reduce moisture levels. However, simply opening windows may not be sufficient, especially during colder months when tenants are trying to conserve heat.
- Condensation control: Condensation is most prevalent in kitchens and bathrooms, particularly in winter. Using extractor fans and ensuring adequate ventilation can help mitigate this issue.
- Positive Input Ventilation (PIV): These systems introduce filtered, fresh air into the property, reducing humidity and condensation levels. PIV systems have been shown to decrease condensation by up to 10%, especially in properties that previously suffered from severe condensation issues
Landlords can expect tenants to take reasonable steps to reduce condensation, such as using extractor fans and heating the property adequately. However, if a tenant reports a mould problem and the local authority deems the complaint valid, landlords are obligated to take corrective measures.
By staying informed and proactive, both landlords and tenants can work together to ensure healthy living conditions and prevent the adverse effects of mould and damp.
