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Mould and damp: what to know and how to deal with it

Reading Time: 5 Mins Read

Mould and damp are common issues in rented properties and inevitably result in tenants requesting that their landlords take action. Mould and damp are unpleasant to live with, cause a variety of health issues and won’t go away unless the underlying causes are addressed. It is vital that mould and damp are not ignored as the longer the problems persist, the worse they will get.

Mould and damp

What is mould and damp?

Damp is the result of too much moisture accumulating inside a building. If the moisture cannot dry out, fungi eventually develops in the form of multicellular thread-like structures called hyphae. These are black in appearance and are referred to as mould.

What are the causes of damp?

There are three types of damprising damp, penetrating damp, and condensation. Each should be treated in a different way, and the potential costs vary considerably.

Rising damp

This type of damp is caused by ground water moving upwards through floors and walls. Most structures allow some water in, but the moisture is usually prevented from causing damage by a barrier called a damp-proof course in walls or a damp-proof membrane in floors. Newer properties will benefit from these features as they are a requirement of building regulations, but older properties may not, and any damp-proofing could have degraded over time. 

The symptoms of rising damp are damaged skirting boards, damp patches on walls and peeling paint or wallpaper. The moisture may dissolve salts in the ground which then leave tidemarks on the walls. If rising damp is present, it is crucial to attend to the damp proof course as soon as possible as the issue will continue to get worse and will eventually damage the structure of the property.

Penetrating Damp

Penetrating damp is caused by water leaking through walls. The damp may expand across your walls or ceiling horizontally, rather than vertically (as is the case with rising damp). This type of damp is usually the result of structural problems such as faulty guttering or roofing and cracks in the walls. It can also be caused by internal leaks from broken piping. 

If penetrating damp is suspected, you should inspect the walls, roof and guttering to establish the cause of the problem. Many of the potential causes are easy to fix yourself but more serious defects will require the services of a building contractor.


This is the most common cause of damp. It is the result of moist air condensing on internal walls and is more prevalent in winter when the walls are generally colder than the air inside the property. The issue will be exacerbated by poor ventilation and the use of periodic heating.  

Where condensation is causing damp, it can be tackled by installing a system to improve ventilation or via the use of dehumidifiers. If left untreated, it will damage plaster and paintwork and cause window frames to decay. 

Day to day activities in the home can make condensation worse. It helps if tenants put lids on saucepans when cooking, dry their washing outside and don’t use paraffin or bottled gas heaters. A bedroom and bathroom window should be opened for 15 minutes each morning and a window should be opened when cooking. Internal doors are best left open so that air can circulate unless tenants are showering or bathing.

How to remove mould

There is no point trying to remove mould until the cause of the damp problem has been found and resolved. Small areas can be removed yourself, but larger areas are better dealt with by professionals as they are a health hazard. 

If you remove the mould yourself, protect yourself from the spores by wearing goggles, rubber gloves and a mask. Open the windows but keep doors closed to prevent the spores from spreading to other areas of the house. Use water and a mild detergent, wipe the mould away with a rag or cloth and try not to brush the mould as you work as this will disperse mould spores. 

Remove any furnishings, clothes and toys which are mouldy in a plastic bag. Furniture can then be shampooed but clothes should be professionally cleaned. Toys are best discarded.

How does mould impact health?

Some people are more sensitive to mould than others. Children, the elderly, people with skin or respiratory issues and those with compromised immune systems are the most vulnerable. 

Moulds produce allergens, irritants and occasionally toxic substances. Inhaling or touching mould spores may result in an allergic reaction or an asthma attack. When inhaled, mould spores can inflame the airways, causing nasal congestion, wheezing, chest tightness, coughing and throat problems. Prolonged exposure to high levels of dampness will reduce lung function and cause chronic health problems including asthma and idiopathic pulmonary haemosiderosis (bleeding from the lung).

Whose should address damp and mould?

It is usually the responsibility of the landlord to deal with any mould and damp which is present at a property. The tenancy agreement should clarify who is responsible for repairs and treatments.  However, a landlord is obliged by law to ensure that their property is fit to live in throughout the duration of the tenancy. It is, however, perfectly acceptable to request that tenants attempt to minimise condensation.  

It is in the interest of both tenant and landlord to deal with damp issues at the first opportunity. Damp and mould will negatively impact the health of those who are forced to live with it but will also worsen over time and cause serious damage to the property. The sooner damp is tackled, the cheaper it is likely to be to solve the problem. 

For more guidance about letting your property or property management, contact us today.

Neil Jennings

Neil is the Operations Director at Assetgrove Lettings, London's Leading Rent Guarantee Company, providing Landlords with no voids, property maintenance, fee-free property management and stress-free service.

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