Understanding Damp and Mould in Homes
Living in a home with damp and mould can be a silent problem that is often overlooked. While it may seem obvious if there are visible signs of dampness, it isn’t always immediately noticeable. This becomes even more challenging when house viewing, as the presence of damp and mould can go undetected.
Estimates suggest that between 4% to 27% of homes in England have damp and mould, which equates to approximately 962,000 to 6.5 million households. The variation in these figures arises from differences in how dampness and mould are measured and reported. Individuals living in private or social rented housing are significantly more likely to experience damp and mould compared to owner-occupiers. In 2024, a survey by Citizens Advice revealed that 45% of private renters were dealing with damp or mould.
Damp not only affects the appearance of a home but can also have serious health implications, especially for those with respiratory conditions like asthma. Two experts in dampness and ventilation have provided insights on how to identify and address this issue.
Common Areas Where Mould Grows
Ruth MacEachern, a ventilation expert and product manager at EnviroVent, explains that mould typically forms in areas with high moisture levels and poor airflow. Bathrooms and kitchens are prime locations due to steam from showering and cooking. However, mould can also appear around windows and window frames, on external walls, and in the corners of rooms where warm air meets cold surfaces.
Other high-risk areas include utility rooms, cupboards, and spaces where furniture is placed directly against walls. These areas can restrict airflow and allow condensation to build up over time, often unnoticed.
Signs of Hidden Mould
It’s common for mould to develop in places that aren’t immediately visible. MacEachern notes that mould can grow behind large items of furniture, inside wardrobes, or in areas that aren’t regularly ventilated, such as cupboards or spare rooms. Condensation can also accumulate within wall cavities or behind plasterboard, meaning mould may be present long before it becomes visible on the surface.
A persistent musty smell is often the first sign of damp and mould. Damian Wallis, a certificated surveyor in structural waterproofing and technical manager for Safeguard Europe, explains that this scent is released by mould spores and can sometimes be detected before growth is visible. He advises following your nose, as the smell will be stronger the closer you get to the source.
Physical Indicators of Dampness
Dampness can affect building fabric in ways that aren’t always obvious. Wallis suggests checking for bubbling or peeling paint, lifting wallpaper, discoloured plaster, and staining around skirting boards. These signs may indicate moisture trapped behind the surface, often due to damp or mould. The surface may feel soft or spongy if pressed, and warped floorboards, swollen timber frames, rusting screws, and crumbling plaster are also warning signs of a damp problem.
Cold walls can also contribute to damp issues. When warm, moist air meets a cold surface, condensation forms. Over time, this moisture can lead to mould growth, peeling paint, and damage to plaster. Wallis explains that trapped moisture-laden air cools when it meets cold wall surfaces, causing condensation that can lead to mould growth. He advises checking behind sofas, bathroom mirrors, cold radiators, and any furniture that sits along the wall, as these surfaces can become cold, damp, and eventually mouldy.
Excessive Water Droplets and Humidity
Excessive water droplets on windows or walls are another indicator of dampness. Wallis notes that while occasional condensation is normal, regular condensation on the inside of windows and walls, especially in bathrooms, kitchens, or rooms where clothes are air-dried, should be investigated. Frequent condensation on surfaces suggests high indoor humidity, often resulting from poor airflow or low room temperatures.
Consistently high humidity, condensation on windows, or sweating walls are warning signs that conditions are right for mould growth. Humidity above 55% is particularly conducive to mould growth.
Health Implications of Mould
Unexplained coughing, sneezing, nasal congestion, itchy eyes, skin irritation, or worsening asthma can be triggered by mould spores. If these symptoms improve when leaving the house, mould could be the cause. Government figures indicate that the presence of damp and/or mould in English residences was associated with approximately 5,000 cases of asthma and 8,500 cases of lower respiratory infections among children and adults. Additionally, dampness and mould were estimated to contribute to one to two per cent of new cases of allergic rhinitis each year.
Addressing Mould in Your Home
If you discover mould in your home, you may wonder whether you can remove it yourself or need professional help. MacEachern states that small areas of surface mould can usually be treated using specialist mould removers or fungicidal solutions, which help to break down and remove mould spores safely. It’s important to wear gloves, ventilate the room well, and avoid simply painting over mould, as this won’t address the underlying issue.
To prevent mould from returning, the root cause must be tackled. In most cases, this means reducing excess moisture through better ventilation. Using extractor fans in kitchens and bathrooms, opening windows regularly, keeping trickle vents clear, and maintaining a consistent level of heating can all help keep humidity under control and prevent mould from coming back.
Sometimes, the cause of dampness can be traced back to the outside of the home rather than the inside. Wallis notes that dampness can seep into the home from a blocked gutter or broken rainwater pipe that directs water into one spot. This type of penetrating dampness left unresolved can spread quickly and cause real damage, so it’s essential to ensure the cause is fully repaired.
