Mouldy House? Causes, Consequences, and Solutions

Mould in the home is a growing crisis. From damp walls to the musty smell that won’t go away, millions of UK households are battling a mouldy house. But what’s really behind these issues, and what can be done to tackle them? In this blog, we’ll dive into the causes, consequences, and solutions to a mouldy house.

The recent Britain’s Mouldy Homes episode from BBC Panorama has once again highlighted the shocking state of rented homes in the UK. With the government estimating that around two million people (3-4% of households) currently live in homes with significant damp and/or mould, it’s clear that this issue goes far beyond aesthetics. It’s a widespread crisis affecting health, wellbeing and housing standards.

In this blog, you’ll learn: 

• The key causes of a mouldy house
• The health risks associated with living in a mouldy environment
• How ventilation and airtightness impact mould prevention
• What the upcoming government regulations mean for landlords
• Practical steps to reduce moisture buildup and improve indoor air quality

Why do so many British homes suffer from mould?

If you’ve ever struggled with persistent mould in your home, you’re not alone. Mould is a widespread issue in the UK, affecting both older properties and modern builds. Several key factors contribute to the problem in British homes:

1. Aging Housing Stock

Many British homes were built before modern building regulations prioritised insulation, airtightness and ventilation. Older homes with solid walls and poor thermal performance are more prone to condensation and mould growth.

2. Damp Climate

The UK’s high levels of rainfall and humidity create ideal conditions for persistent dampness, especially in coastal and high-rainfall regions.

3. Energy Efficiency Upgrades Without Ventilation Considerations

Improving airtightness through insulation, double glazing and draught-proofing helps retain heat but can also trap moisture if ventilation isn’t upgraded alongside it. Poor moisture management when upgrading a home can lead to unintended mould problems.

4. Social Housing & Maintenance Issues

The BBC Panorama investigation Britain’s Mouldy Homes highlighted how tenants in social housing struggle to get landlords to take action. Delayed repairs, inadequate ventilation and poor heating systems often allow mould problems to persist.

5. Rising Heating Costs & Underheating Homes

As energy costs rise, many households cut back on heating, making surfaces colder and increasing condensation risk. Without proper ventilation, underheated homes create the perfect environment for mould to thrive.

What Causes a Mouldy House?

While external factors contribute to the UK’s mould crisis, specific conditions inside your home determine whether mould will take hold. Understanding these key causes is the first step toward finding an effective solution:

• Condensation Buildup: Moisture from everyday activities (cooking, showering, drying clothes) lingers without proper ventilation, leading to damp conditions.
• Leaks and Water Ingress: Roof leaks, plumbing issues, and poorly sealed windows allow moisture to seep into the building fabric.
• Poor Insulation & Heat Loss: Cold surfaces due to insufficient insulation or air leakage lead to condensation, which encourages mould growth.
• Ventilation Issues: Homes that are too airtight without proper airflow trap humidity, creating persistent damp problems

Many people attempt quick DIY fixes like scrubbing away mould, but without addressing these underlying causes, the problem will return. The key to a mould free home is balancing airtightness and ventilation to manage moisture effectively.

The Link Between Ventilation, Airtightness, and Mould

While an airtight home helps with energy efficiency and preventing heat loss, it can also lead to moisture buildup if proper ventilation is not in place.

When a home is too airtight without adequate ventilation, moisture from everyday activities like cooking and showering has nowhere to escape. This trapped humidity then condenses on cooler surfaces, creating the perfect conditions for mould growth. On the other hand, excessive air leakage can introduce damp air from outside, exacerbating existing moisture issues.

The Health Risks of Living in a Mouldy House

Scientists from the UK Health Security Agency have identified a significant burden of respiratory illness due to residential damp and mould exposure. With 2 million people in England living in affected homes, vulnerable groups – including children, the elderly, and those from disadvantaged communities – face the highest risks. With ethnic and minority and disadvantaged groups found to be disproportionately impacted by damp and mould, this reflects a wider issue of environmental health inequity.

Studies have linked indoor mould exposure to:

• Respiratory issues (asthma, chronic cough, wheezing)
• Allergic reactions (skin irritation, watery eyes, sneezing)
• Weakened immune responses, particularly in children and the elderly

The tragic case of Awaab Ishak, a two-year-old who died in 2020 due to prolonged mould exposure, was a wake-up call for both landlords and tenants. His death has led to Awaab’s Law – new government legislation aimed at tackling unsafe living conditions, set to come into force later this year. These new laws will require landlords to take proactive steps to prevent damp and mould or face legal consequences.

Want to know how to stay compliant? Read our full guide on the upcoming regulations – coming soon.

Effective Solutions: Quick Fixes vs. Long-Term Prevention

While it may be tempting to wipe away mould and move on, true prevention requires addressing the root causes. Here’s how to tackle the problem effectively:

Quick Fixes – Temporary Solutions

• Wiping away visible mould – removes surface growth but doesn’t stop regrowth.
• Using mould-resistant paint – offers short-term protection but doesn’t address moisture issues.
• Opening windows for airflow – helps reduce humidity but is less effective in colder months.

Long-Term Solutions – Preventing Mould at the Source

• Proper Ventilation Systems – Mechanical ventilation with heat recovery (MVHR), extractor fans and passive vents help regulate indoor air quality and remove excess moisture.
• Balancing Airtightness & Insulation – Ensuring homes are well-insulated while allowing controlled airflow prevents condensation on cold surfaces.
• Fixing Structural Issues – Addressing leaks, improving drainage and sealing gaps prevents moisture ingress and long-term damp problems.
• Using Dehumidifiers – Helpful in particularly damp areas to maintain optimal humidity levels.

By combining improved ventilation, insulation and moisture control, you can create a healthier, mould free home.

Ventilation Testing

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What’s Next?

Don’t let mould put your health at risk. If you’re struggling with persistent damp and mould, our experts can diagnose the root causes with professional air tightness and ventilation testing followed by tailored recommendations to prevent mould at the source.

Contact us today for expert guidance on keeping your home healthy, safe and compliant.