You may think that if you’re living in a house with damp and mould, you’d be aware of it, but it isn’t always immediately obvious. And it becomes even harder to spot if you’re house viewing.
Estimates of the number of homes in England with damp and mould range from four to 27 per cent, or 962,000 to 6.5 million households. The reported figure varies due to differences in how dampness and mould are measured and reported. While people living in private or social rented housing are significantly more likely to live in a home with damp and mould than owner-occupiers. In 2024, Citizens Advice found that 45 per cent of private renters were experiencing damp or mould.
Damp doesn’t just look bad, but it can impact your health if left untreated – especially if you suffer from respiratory problems like asthma. Here, two dampness and ventilation experts explain how to spot mould, where it commonly grows, and what to do about it.
Where are the common areas where mould can grow?
Ruth MacEachern, ventilation expert and product manager at EnviroVent, says: “Mould tends to form in areas of the home where moisture levels are consistently high, and airflow is poor. Bathrooms and kitchens are some of the most common hotspots due to steam from showering and cooking, but it 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 pushed directly up against walls, which can restrict airflow and allow condensation to build unnoticed over time.
Can you have mould in your house and not see it?
MacEachern says it’s very common for mould to develop in places that aren’t immediately visible. “In many homes, 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 build up 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
For many, an earthy or musty smell is the first sign that damp and mould are present. According to Damian Wallis, a certificated surveyor in structural waterproofing and technical manager for Safeguard Europe. “This tell-tale scent is released by mould spores, and can sometimes be detected before growth is visible. Follow your nose; the smell will be stronger the closer you get to the source.”
Bubbling or peeling paint
Dampness affects building fabric in ways that may not be obvious. Wallis advises that you check for bubbling or peeling paint, lifting wallpaper, discoloured plaster, and staining around skirting boards, as this may indicate moisture trapped behind the surface, often due to damp or mould. “The surface may feel soft or spongy if pressed. Warped floorboards, swollen timber frames, rusting screws and crumbling plaster are also warning signs of a damp problem,” says Wallis.
Cold walls
Cold walls do more than make a room uncomfortable. When warm, moist air inside your home meets a cold surface, condensation forms. Over time, this moisture can lead to mould growth, peeling paint and damage to plaster.
As Wallis explains: “Trapped moisture-laden air cools when it meets cold wall surfaces and causes condensation that can lead to mould growth. Check behind sofas, bathroom mirrors, cold radiators and any furniture that sits along the wall as these surfaces can become cold, damp and eventually mouldy. Built-in cupboards, particularly on external walls, can also be affected by mould due to cold surfaces and poor air circulation.”
Excessive water droplets on windows or walls
Wallis says that while occasional condensation is normal, investigate when it appears regularly on the inside of windows and walls, especially in bathrooms, kitchens or rooms where clothes are regularly air-dried. “Frequent condensation on surfaces suggests high indoor humidity,” he says. “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 per cent is particularly conducive to mould growth.
You have allergy-like symptoms
As well as physical signs in the property, unexplained coughing, sneezing, nasal congestion, itchy eyes, skin irritation, or worsening asthma can be triggered by mould spores. If you find these symptoms improve when you leave the house, mould could be the cause.
According to government figures, the presence of damp and/or mould in English residences was estimated to be associated with approximately 5,000 cases of asthma and 8,500 cases of lower respiratory infections among children and adults. In addition, dampness and mould were estimated to contribute to one to two per cent of new cases of allergic rhinitis per year.
How do I get rid of mould in my house?
If you have mould, you may wonder if you can remove it yourself or need to call in the experts. MacEachern says 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.”
However, to stop mould from returning, the root cause needs to be tackled. In most cases, that 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. This 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. Dampness can seep into the home from a blocked gutter or broken rainwater pipe that directs water into one spot,” says Wallis. “This type of penetrating dampness left unresolved can spread quickly and cause real damage, so make sure the cause is fully repaired.”