When we think of damp and mould, most of us picture cold, draughty winter days. But these issues don’t disappear in the summer—in fact, warmer months can create the perfect breeding ground for mould, especially in older London properties.
If you’re a landlord, keeping on top of summer mould and damp is just as important as preparing for winter. Not only does it protect your property, it ensures your tenants stay happy, healthy, and safe.
Why does mould appear in summer?
Although winter mould is usually linked to cold surfaces and condensation from inadequate heating, summer mould tends to stem from excess humidity. When the air is warm and moisture levels are high, poorly ventilated homes can become ideal environments for mould growth.
Several common scenarios contribute to this:
Lack of airflow: Tenants may keep windows closed to block out hot air or noise, limiting natural ventilation.
Indoor drying: Washing left to dry inside, especially without open windows or a dehumidifier, can dramatically raise humidity.
Plumbing issues: Leaky taps, hidden pipe damage, or inefficient drainage can go unnoticed during summer when heating systems are off.
Heavy rainfall: Summer showers can still lead to water ingress or rising damp, particularly in basement flats or buildings with poor drainage.
In London, where many rental properties are conversions or older buildings, these factors can be especially problematic.
What should landlords look out for?
It’s important to recognise the early signs of summer damp and mould before they escalate into costly repairs. Keep an eye—or ear—out for:
A persistent musty smell, even if the home appears clean and dry
Black or green mould patches on walls, ceilings, window frames, or behind furniture
Paint or wallpaper that’s peeling, bubbling, or discolouring
Damp areas around skirting boards or near the floor, which may indicate rising damp
Tenants may not always report these issues straight away, especially if they assume it’s minor. Regular inspections and open lines of communication can help catch problems early.
Preventing summer mould: practical steps
While some causes of damp are structural, many can be prevented with a few proactive measures. Here’s what you can do:
Ensure good ventilation: Make sure extractor fans in kitchens and bathrooms are working efficiently. Consider installing trickle vents in windows if they aren’t already in place. Encourage tenants to open windows regularly, particularly after cooking or showering.
Address repairs quickly: A minor leak in summer can easily develop into a major damp issue if left unchecked. Respond promptly to repair requests and carry out routine checks between tenancies.
Use protective materials: In rooms that are particularly prone to damp, using mould-resistant paint and anti-condensation coatings can offer added protection.
Provide dehumidifiers: If a property naturally retains moisture—such as a basement flat—it may be worth supplying a dehumidifier. Some landlords even include it as part of the tenancy agreement.
Educate your tenants: A short welcome guide with advice on preventing mould (like keeping bathroom doors closed when showering or not drying laundry on radiators) can make a big difference. It’s not about blaming tenants, but empowering them with knowledge.
Your legal responsibilities
Under UK law, mould and damp fall under the Housing Health and Safety Rating System (HHSRS), which means landlords are responsible for keeping their properties free from hazards. If a tenant reports mould and it’s not resolved, they may contact the local authority, who could issue an enforcement notice or fine if the issue is deemed serious.
Ignoring these problems risks not just damage to your property, but your reputation and legal standing too.
How Letio supports landlords
At Letio, we understand how important it is to keep rental properties in good condition year-round. Whether it’s dealing with maintenance concerns or supporting tenants in reporting issues early, we’re here to help landlords stay ahead of problems like damp and mould.
We pride ourselves on clear communication, reliable service, and a straightforward approach—so you can feel confident your property is being looked after properly.
