A landlord’s guide to

combatting condensation and mould

Welcome to our guide on combatting condensation and mould, two familiar foes in many rented (and owned) homes across Leicester. 

We’ve used our 30+ years of experience in lettings to provide practical advice, clear explanations, and effective remedies to condensation and mould problems.

Understanding the causes, identifying problem areas and implementing effective measures are crucial steps in successfully addressing these issues.

It’s also important to remember that pretty much every property in the UK, due to our climate, gets a degree of condensation and – to a varying degree – mould.

This guide is designed to be a helpful resource, providing easy-to-follow advice, from identifying high-risk areas in your rental property to adopting long-term strategies to combat condensation and prevent mould growth.

We’ve also created a version of this guide for tenants, as in our experience, educating tenants about the causes and issues around condensation goes a long way to solving them.

As a landlord looking to safeguard your property, this guide, like everything we strive to do as an agency, has got you covered.

What are condensation and mould?

In this section, we delve into what condensation and mould are, why they occur and how they can impact your rental property and your tenant’s enjoyment of it. But why is condensation a concern? When excess moisture accumulates, it creates ideal conditions for mould growth. Mould, a fungus, thrives in damp, poorly ventilated areas.


It can spread quickly, causing damage to your property and, in severe cases, potentially lead to health issues, especially for those with allergies or respiratory problems.

Condensation is when warm, moist air meets a colder surface, turning water vapour into liquid. This often happens in homes during colder months (but can occur in summer, too) when heating systems are on and windows are closed, creating a perfect environment for condensation.

An important point here is not to panic – mould that causes health problems is extremely rare. This is somethingwe emphasise to tenants.

Understanding the ‘dew point’ is key. It’s the temperature at which air can no longer hold all its water vapour, causing it to to condense into water droplets. In properties, this often occurs on cold surfaces like windows or walls. Keeping indoor humidity at a balanced level is crucial in preventing the dew point from being reached inside your property.

Recognising the first signs of condensation and mould is the first step in tackling them.

From here, we will explore how to identify high-risk areas in your property and the common causes that contribute to these issues

💡 Top Tip: Install or upgrade extractor fans, especially in kitchens and bathrooms.

The places condensation and mould love

Let’s identify the common places where condensation and mould are most likely to occur on your property. Understanding these areas can help landlords and tenants focus their prevention and treatment efforts more effectively.

1. Kitchens and bathrooms

These areas are moisture hotspots due to cooking, boiling water and bathing. Without adequate ventilation, this moisture lingers and condenses on cooler surfaces

2. Cupboards and wardrobes

Tucked away and often poorly ventilated, these spaces can become mould havens, especially if they are against external walls.

3. Windows and windowsills:

Condensation frequently forms on windows, particularly during cold months, leading to mould growth on sills and frames.

4. Basements and cellars:

Often having poor ventilation and being prone to damp, these lower levels of a property are common sites for mould.

5. Behind furniture and appliances:

Areas behind large pieces of furniture or appliances, like fridges, that are rarely moved or cleaned behind, can be hotspots for mould.

6. Ceiling corners and wall joints:

These areas can harbour condensation and mould due to less air circulation.

By identifying these high-risk areas, landlords and tenants can take targeted action to reduce the development of condensation and mould.

Regular checks and maintenance of these areas are vital in preventing mould growth and maintaining a healthy living environment.

Unveiling the causes of condensation and mould

Understanding the common causes of condensation and mould is crucial in effectively combatting them. Here, we highlight the typical lifestyle and environmental factors contributing to these issues. Weeducate your / our tenants about these.


More people in a space means more moisture from breathing and perspiration. The average adult releases around 400g of water daily – just by breathing.

Tumble drying and cooking

These activities can release significant moisture into the air without proper ventilation.

Lack of airflow

Poor ventilation traps moist air inside, especially in modern, well-sealed properties.

Rarely opened windows

Fresh air helps to reduce indoor humidity levels– and closed windows prevent this exchange

Drying clothes indoors

Wet clothes significantly increase indoor humidity.

Cold indoor temperatures

Warm air holds more moisture; when it cools, condensation occurs.

💡 Top Tip: Keep heating systems in good working order to ensure consistent, moderate temperatures.

A step-by-step guide to mould removal

Dealing with existing mould is crucial in maintaining a comfortable, cleaner property. This section provides a safe and effective process for cleaning mould from your rental. We share this process with tenants.

Thinking longer term

Investing in long-term strategies is essential for effectively reducing condensation and mould risks and creating a cleaner, more comfortable property. Here are some sustainable solutions for landlords to consider investing in.

Upgrade to humidistat-controlled extractor fans

These advanced fans activate upon detecting high humidity, ensuring optimal ventilation in kitchens and bathrooms.

Enhance insulation

Effective insulation in walls and lofts is vitalfor maintaining consistent indoortemperatures and preventing condensationon cold surfaces. Beyond mould prevention,it also improves energy efficiency and canlower heating costs.

Install trickle vents

Trickle vents – small openings in windows or walls – allow controlled natural ventilation, essential for reducing indoor humidity, particularly in modern, well-sealed properties.

Positive input ventilation (PIV) units

PIV systems introduce and circulate fresh, filtered air throughout the property, displacing stale, moist air. This reduces humidity and enhances air quality, especially in properties struggling with persistent condensation and mould. Be warned, though, these can be costly.

Regular maintenance

Ensuring ventilation systems and dehumidifiers are in peak condition is vital. Regularly servicing these systems, particularly humidistat fans and PIV units, is crucial for maintaining optimal humidity levels.

Don’t panic – Here’s why

As we conclude our guide, it’s important to remember that condensation and mould can be concerning, but they are easily manageable with the right approach.

Condensation and mould are common and usually straightforward to sort out.

  • Perform routine checks for early signs of mould and moisture.
  • Aim for a healthy balance of humidity, temperature and air circulation.
  • A good letting agent can offer you and your tenants expert advice and practical solutions.
  • Keep up to date with home ventilation and moisture control advancements.
  • Regular maintenance of your property can prevent mould issues.
  • Consider smart home devices for efficient indoor environment management.

Knightsbridge Estate Agents & Valuers – Company Number: 03895928

Knightsbridge Professional Lettings – Company Number: 09983885

Registered Address: 72 Queens Road | Clarendon Park | Leicester | LE2 1TU

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