Tenants typically complain their property is damp and mouldy, and want their landlord to take action. Landlords, on the other hand, tend to blame tenants’ lifestyles for the problem.
Obviously, damp issues are not limited to properties in the private rented sector – owner-occupiers suffer too.
In either case, the big question is: how do you know if the building itself or the occupiers’ lifestyle is the cause?
There are three main causes of damp in a residential property: condensation, rising damp,
and penetrating damp. Each need to be treated in a different way, so it’s vital property owners understand what’s causing the damp before spending money on expensive damp treatments.
We explain what these types of damp are and how you can combat them.
Tackling condensation in five steps
Condensation is by far the most common type of damp. Rentokil Property Maintenance estimates that condensation affects one in five properties in the UK.
Why properties suffer from condensation is down to science. Even if you can’t see it, there is always a certain amount of moisture in the air. Everyday routines such as washing, cooking, drying clothes, and even just breathing, release moisture into the atmosphere. The average family of four produces about 24 pints of water vapour in just 24 hours.
When the air contains more moisture than it can hold and comes into contact with a cold surface, such as a window or wall, the moisture in the air turns into droplets of water.
This leads to damp patches on the inside of external walls, in the corners of rooms, on window frames, and behind furniture. The damp patches then cause mould to grow. Condensation is mainly a winter problem, as walls are much colder than the air inside a property. Here’s how to tackle problem condensation:
Landlords need to start by ensuring rented properties are equipped with adequate heating. Central heating usually takes the form of either a gas boiler and radiators, or electric storage heaters.
Tenants and owner-occupiers need to learn how to use central heating in the right way. Phil Harrison, head of domestic sales at ventilation company EnviroVent, says: “Warmer air can hold more moisture, so keeping the temperature at a consistent 18°/19°C is better than ‘blasting’ the heating once or twice a day for an hour at, say, 25 °C. Maintaining a reasonable and consistent temperature will not only be more comfortable for the occupants, it will also usually be cheaper than the ‘blasting’ method of heating a home.”
Decent insulation can prevent ‘cold spots’ where condensation might form. Insulation stops a home from losing heat as well as keeping it cooler in the summer and limiting noise pollution.
Simple ways to reduce heat loss include fi tting carpets, curtains, and draught excluders.
Heat loss through windows can be reduced using double glazing, while heat loss through walls can be reduced using cavity wall insulation. This involves blowing insulating material into the gap between the brick and the inside wall, which reduces the heat loss by conduction.
The material also prevents air circulating inside the cavity, therefore reducing heat loss by convection. You can reduce heat loss through the roof by laying loft insulation, which works in a similar way to cavity wall insulation.
From April 2018, it will be illegal to let domestic properties below a certain effi ciency standard, and fines will be imposed on landlords who don’t comply.
Experts say adequately ventilating a property requires a joint effort between landlords and tenants. But while landlords often suggest tenants open windows on a daily basis, this can be impractical as well as insuffi cient.
Fortunately, there are other steps property owners can take to improve ventilation: adding air bricks (special bricks containing holes that allow air to enter) to the outside walls, installing window vents at the top of windows, or adding air vents to internal walls or sealed
chimneys. There should also be fans in both the kitchen and bathroom as these two rooms are responsible for most of the moisture in the home.
The people living in the property should keep any vents open all the time, not obstruct air blocks, and use any fans installed.
You can also adopt some simple lifestyle changes to reduce the amount of condensation in a property. These include only boiling the right amount of water needed for a hot drink, closing the bathroom door while showering, and putting lids on pans while cooking.
Clothes shouldn’t be dried on a radiator, and if a tumble dryer is used it should be ventilated to the outside.
Chris Norris, head of policy at the National Landlords Association, says tenants can also tackle the build-up of condensation by wiping any excess moisture away where it accumulates. “If mould starts to appear as a result of poor ventilation, then tenants should take action to remedy the situation and inform their landlord. It may be that mechanical ventilation is possible or that a dehumidifier would improve matters, in which case the landlord is likely to favour taking preventative action to ensure problems don't occur further down the line," he says.
Various mechanical ventilation devices are sold and installed by companies such as EnviroVent, Nuaire, Rentokil and Kenwood.
EnviroVent’s Mr Harrison recommends a positive input ventilation (PIV) system with effective humidity and vapour tracking fans. “The PIV system will gently ventilate the property continuously, while the fans get rid of the excess moisture at source – in the bathroom and kitchen. It is vital that any ventilation systems installed are done so correctly and by a qualified and competent expert to ensure they work as intended and provide the solution required.”
Property owners should expect to pay about £1,000 for a PIV system to be supplied and installed.
Damp: a more costly problem
If a rented property suffers from rising or penetrating damp, it is the landlord’s responsibility to get it treated. A damp specialist, builder or surveyor can assess which type of damp is present and suggest a solution.
Rising damp is moisture present in walls as a result of water in the ground underneath or next to the walls rising up through the fabric of the wall. It is usually identified by blistered paintwork, peeling wallpaper or damp patches on walls. Rising damp is more prevalent in, but not limited to, older properties.
“The speed at which this process occurs depends on many things, including the nature of the ground, type of wall or floor construction, and environmental conditions both inside and outside the building,” says Berwyn Evans, UK product manager of Rentokil Property Care.
“There are often groundwater salts (chlorides and nitrates) dissolved in the rising water and as it evaporates, these salts become concentrated in the plaster and often leave a discoloured line that shows how far the water has risen.”
Damp proofing is a general term that covers methods used to prevent damp from being absorbed through walls or floors into the interior of a property.
There are many legitimate damp proofing companies around, but if you want to avoid the inevitable rogues in the industry, it is best to opt for a Which? Trusted Trader or a member of the Property Care Association. Be aware that damp proofing can be expensive. According to Aviva, damp proofing a typical three-bedroom house will cost between £3,000 and £4,000.
Penetrating damp is classed as any water that finds its way inside from the outside.
It can be caused by defects in a property such as cracked render, gaps around windows, broken guttering, leaking roofs, and plants that grow on the outside of the building.
“In either rising or penetrating damp, it is solely the responsibility of the landlord to remedy these issues as they are the result of defects to the exterior of the property,” says David Cox, managing director of the Association of Residential Letting Agents.
“This type of damp is remedied by reinforcing or reinstating the damp proof course, remedying any other defect that may have caused or contributed to the original breach and then drying out the property through a combination of heating and ventilation.”
Living in a damp property can damage your health
Mould found on windows, walls, and even in bedding can cause severe reactions for those with allergic conditions. Microscopic mould spores can get into the airways and sinuses, causing infections that are diffi cult to treat.
“Mould can be responsible for triggering allergies, eczema, asthma and, in some cases, pneumonia,” says Dr Tim Lebens, a Doctify GP. “If you are suffering from any respiratory symptoms, such as a tight chest, breathlessness, wheeze or cough, then you should consult a doctor."
Will insurance cover the problem?
Buildings insurance or landlord insurance should provide cover for structural damage to the building caused by penetrating or rising damp, but not condensation.
“If the property has been maintained properly and suffers damp or mould due to an ingress of water following an insured event, then a claim for damp or mould may be successful,” says Gary Holmes, underwriter at Direct Line for Business. “Insurers will need to look at each claim on a case-by-case basis, but it is the landlord’s responsibility to ensure the property is maintained to a good standard.”