Condensation and mould aren’t just unsightly; they can damage your home and pose health risks. In winter, many homeowners notice droplets running down windows or black spots in corners. As someone who grew up in a draughty Victorian house in Surrey, I remember wiping condensation off the sills every morning. That damp, musty smell isn’t something you forget. With energy prices high and our climate getting wetter, it’s more important than ever to keep our homes dry, warm and healthy. This guide explores why condensation happens, how it affects health and the steps you can take to prevent it.
Why condensation forms
Condensation occurs when warm, moist air meets a cooler surface and the water vapour turns back into liquid. Common sources of moisture include cooking, showers, drying clothes indoors and even breathing. In poorly insulated or ventilated homes, that moisture has nowhere to go. Kitchens and bathrooms are particularly prone to condensation because of the amount of steam produced. During cold months, the temperature difference between indoor air and cold walls or windows is greater, meaning vapour is more likely to condense.
Health effects of damp and mould
Damp and mould can have serious health implications. Government guidance notes that damp and mould primarily affect the airways and lungs and can cause serious illness; symptoms can range from coughing and eye irritation to asthma attacks. People with existing respiratory conditions, children and older adults are especially vulnerable. Prolonged exposure can also affect mental well-being by creating unpleasant living conditions and causing anxiety about the state of your property. Addressing condensation isn’t just about preserving your home; it’s also about protecting the health of everyone living there.
Improve ventilation
The simplest way to control condensation is to let moist air escape. Open windows daily, even in winter, to allow cross-ventilation. Fit extractor fans in kitchens and bathrooms and use them during and after cooking or bathing. Leave internal doors open when possible to help air circulate. In bedrooms, avoid blocking air vents or trickle vents in window frames—these small openings help draw fresh air in without creating draughts.
Use dehumidifiers
If you’re dealing with persistent moisture, a dehumidifier can be a lifesaver. These machines pull excess water from the air and are particularly useful in rooms where laundry dries or in basements. They’re quiet, efficient and can prevent condensation on walls and windows.
Maintain consistent temperatures
Large temperature swings encourage condensation because warm, moist air cools quickly on colder surfaces. Keep your home at a steady, comfortable temperature, even overnight, to prevent cold spots forming on walls and windows.
Programmable thermostats and smart heating controls can help maintain a constant temperature without wasting energy.
Invest in quality insulation
Poor insulation is one of the leading contributors to condensation. Insulating external walls raises the temperature of internal surfaces, making it less likely for moisture to condense. High-quality insulation also improves energy efficiency, keeping your home warmer and cutting heating bills. If you live in an older property, consult a professional about external or internal wall insulation options. On a smaller scale, draught-proofing windows and doors with seals and weather-stripping reduces cold air infiltration and helps maintain consistent temperatures.
Try anti-condensation paint
Specialist paints contain micro-beads or insulating materials that keep wall surfaces slightly warmer, reducing the likelihood of condensation forming. These paints are ideal for bathrooms, kitchens and other problem areas and can be applied as part of a redecoration project.
Control indoor humidity
Simple lifestyle changes can make a big difference. Cover pans when cooking, use lids on boiling pots and run the cooker hood. Dry clothes outdoors or in a vented tumble dryer. Avoid using unflued gas heaters, which release moisture into the air. Houseplants can help absorb some humidity, but avoid having too many in small rooms as they can add moisture. Monitor humidity with a digital hygrometer and aim for around 40–60% relative humidity.
Seal gaps and cracks
Gaps around window and door frames allow cold air in and warm air out, creating cold surfaces for condensation to form. Seal any cracks with caulk or weather-stripping. Check exterior masonry for cracks or missing mortar and repair as necessary. Ensure roof tiles and gutters are in good condition to prevent rainwater ingress, which can lead to both penetrating damp and condensation.
Positive Input Ventilation (PIV) systems
PIV systems draw fresh, filtered air from outside and introduce it into your home, pushing out stale, moist air. They are particularly useful in properties with persistent condensation problems. PIV units are installed in the loft or on a wall and run quietly in the background. They can significantly improve indoor air quality and prevent mould growth.
Regular cleaning and maintenance
Wipe down condensation on windows and walls as soon as you see it to stop mould from taking hold. Use mould-removal sprays or a mild solution of bleach and water to clean affected areas and wear gloves and a mask to protect yourself. Wash or replace mouldy curtains and soft furnishings. Once you’ve cleaned away mould, keep checking the area regularly.
Professional assessment
If you’ve tried these steps and still struggle with damp or mould, seek professional help. Specialist surveyors can diagnose the cause of damp, check for hidden leaks and recommend solutions tailored to your home. Sometimes, underlying structural issues such as damaged pointing, defective gutters or a compromised damp-proof course are to blame. Professional treatment may involve installing improved ventilation, applying damp-proof membranes or upgrading insulation. For professional damp surveys and treatments, see Go2 Damp Proofing services.
Conclusion
Condensation and mould are problems that many UK homeowners face, especially in older properties. By understanding why condensation happens and taking practical steps—improving ventilation, maintaining consistent temperatures, insulating walls and making small lifestyle changes—you can create a healthier, drier home. Remember, tackling condensation not only protects your property but also safeguards the health and comfort of everyone inside. Persistent issues should always be assessed by professionals, as the right diagnosis and treatment can save you time, money and stress in the long run.