Unfortunately, damp is a common problem affecting any property, regardless of age. It comes in various guises and can be caused by a variety of factors, but the most feared of all – and often the costliest to fix – is rising damp.
While rising damp is relatively rare compared to other forms of damp, such as condensation and penetrating damp, don’t be alarmed, as there are things you can do to treat it. Also, it usually only affects older properties, such as grade 2 listed properties, which may not have a damp-proof course, or if they have, it can become damaged over time and lead to damp spreading.
- Understanding rising damp
- Effects of rising damp
- Solutions for rising damp
- Insurance and legal considerations
What is rising damp?
Rising damp occurs when groundwater creeps up the walls and/or through the floors of a building by a process known as ‘capillary action’. Building materials such as bricks, mortar, and cement are porous, so they can absorb and draw moisture upwards, just as a piece of string would if you dangled the end of it in a jar of water.
Where does rising damp start?
If the property has no damp-proof course inside its walls or damp-proof membrane under its concrete floors – or if these protective layers are damaged – then the water is able to rise up above the foundations and could eventually become apparent in your ground-floor rooms.
Rising damp can also be caused by the ground level being raised – for example, if a heap of earth is piled up against an exterior wall or an area next to the building has been concreted over or paved. If the ground surface next to the walls becomes higher, it can act as a ‘bridge’ for rising groundwater, allowing it to bypass the damp-proof course. The situation can worsen if there is inadequate drainage to carry rainwater away from the building.
What does rising damp look like?
It can usually be identified by the presence of damp patches near the base of internal walls (up to around 1.2m) or on floors at ground level. But rising damp can also cause rotting skirting boards or floor timbers; peeling paint or wallpaper; stains or tidemarks; crumbling plaster; a musty smell; mould; and powdery salt residues left behind on the wall or floor surface as the groundwater evaporates into the room.
Is rising damp seasonal?
As rising damp is the result of moisture being sucked up from the ground, you’ll find it is most prevalent when the water table is high and there are large amounts of groundwater present. Therefore, it will tend to be more noticeable during the wetter months of the year, from the onset of autumn, through winter, and into spring, but will be less apparent as the weather improves through late spring into summer.
What is the main cause of rising damp?
A range of factors can cause rising damp, but the most important ones to be aware of are –
- An absence or the failure of a damp-proof course.
- Historically damp-proof courses were made of slate, which may fracture over time.
- Damp-proof courses can become externally bridged by a rise in the ground level or internally by inserted solid floors.
- An absence or the failure of a link between the damp-proof membrane and damp-proof course.
- The use of impervious surface finishes, such as cement-based renders, will prevent moisture evaporating from within a wall, causing it to seek an alternative route out.
- A hard surface around the outside base of a wall will prevent groundwater evaporating and could cause surface water to flow back towards a building.
Is rising damp the same as mould?
Rising damp can lead to the growth of mould, so rather than being the same thing, rising damp creates favourable conditions for mould to grow.
Can you smell rising damp?
In short, yes. You are most likely to notice a moist and musty smell in areas affected by rising damp, and it is important to pay attention to these as you may become aware of the smell before you notice any visual appearance of damp.
What are the dangers of rising damp?
Rising damp has the potential to become more than just an unsightly stain on the wall. If left untreated, it can lead to structural damage, especially if timbers begin to rot and decay, and it’s likely to put off prospective buyers if you’re looking to sell your property.
How common is damp in houses?
While rising damp isn’t very common due to the circumstances that cause its development, other forms of damp such as condensation or penetrating damp, sometimes caused by escape of water, are also of concern.
According to a 2021 YouGov poll commissioned by the charity Shelter 26% of all renters reported that their housing was affected by damp and mould. If you rent your property and suspect it has rising damp, report it to your landlord and ask them to get a professional to conduct further investigation.
How much does rising damp devalue a house?
Buyers will rightly be wary of purchasing a property with signs of damp, but the severity and the reason for it will affect the price. Basic condensation is unlikely to make much difference. More serious issues such as rising damp can result in anything from 10% up being knocked off the value of your home. In severe cases, where damp has been left untreated for a long period of time, the impact on price could be even more significant.
Can you sleep in a room with rising damp?
While rising damp itself is not a threat to your health, it often leads to other issues, such as increased humidity and the growth of mould, which can become problematic and is, therefore, best avoided.
Can you get sick from rising damp?
Living in damp and mouldy conditions can have an impact on health, causing respiratory infections, allergies, asthma and/or a weakened immune system – especially in young children, the elderly, and those with existing health problems.
Visit the NHS for more information.
Can rising damp be treated?
The good news is that rising damp can be treated. Before doing so, though, it’s advisable to confirm your suspicions with a professional diagnosis which you can get by commissioning a qualified damp surveyor, rising damp treatment specialist, or preservation company.
Can rising damp be permanently fixed?
With the correct treatment, you should be able to remedy any problems you have with rising damp. A professional diagnosis will provide you with details of the issues affecting your property and recommend the most appropriate treatment option.
How do you treat rising damp in an old house?
The first thing to do is to check that you have a damp-proof course and damp-proof membrane, which should prevent groundwater from soaking into your walls and floors.
They’ve been a compulsory feature in houses built since 1875, so if your house was built prior to then, it’s likely that it won’t have them. Take a look at your external walls, and you may be able to spot a thin strip slightly above ground level, but an expert will be able to confirm either way.
However, if they are present and you’re experiencing damp, it’s possible that they have become damaged or worn over time, so you’ll need to get them repaired or replaced.
The most common treatment for a damaged or missing damp-proof course involves drilling holes into the affected wall and injecting it with a damp-proof cream which acts as a new course.
A more invasive solution involves cutting grooves into the brickwork so that you can install a new piece of damp-proof course, but this approach is more complex and time-consuming.
How long does it take to fix rising damp?
The work itself generally only takes a few days, but it’s important to remember that you’ll also need to allow time for everything to dry out thoroughly before you replaster and decorate.
The British Board of Agreement (BBA) certifies damp-proofing products and recommends that new plaster should not be applied for at least 14 days after injecting the damp-proof treatment, while the damp-proofing industry’s Code of Practice states that walls can take 6 to 12 months to dry out fully and that adding paint or render to a wall will substantially extend this drying period.
Thicker walls will also take longer to dry out, but in general, it’s best to allow one month per 25mm thickness of wall to dry once the cause of the rising damp has been remedied.
Does opening windows reduce damp?
Opening your windows won’t rectify the issues causing rising damp, but it will reduce the amount of humidity in your property, which in turn will lead to a decreased chance of condensation, which can cause general damp in a property.
How do you clean damp walls?
The simplest option involves adding some detergent, such as washing-up liquid or a mild bleach, to a bucket of warm water and, using a cloth, wipe the mould away. If you’re experiencing heavier mould growth, you’ll likely need a specialist mould removal product, which you’ll find in all the main supermarkets.
Which paint is best for damp walls?
All the major paint brands offer a damp seal paint which can be used as an undercoat before adding the colour of your choice. Most only require a single coat and will act as a barrier to the development of moisture.
It’s important to note that while damp-proof paints are a useful addition when you decorate, they won’t address the cause of the damp, so at best will only act as a temporary fix.
Does heating stop rising damp?
No, having your heating on can help to reduce condensation and the damp that this causes, but it won’t help with rising damp because a structural issue is causing this.
Is rising damp covered by house insurance?
The answer is most likely to be ‘no’. It’s not usual for buildings, contents, and landlord insurance policies to cover gradual deterioration, which is the category that damp problems generally fall into. This is especially true of rising damp, which insurers tend to consider as only ever being associated with a gradual decline in the condition of the building.
Can I claim for rising damp on my home/landlord insurance policy?
It’s worth double-checking the exclusions listed in your policy documents first, but the likelihood is that you’ll need to arrange and fund the repairs yourself. Be sure to consult several reputable damp specialists before proceeding with any work to ensure the damp problem in your property is properly diagnosed and that you pay a fair price.
Can you sell a house with damp?
You can certainly sell a house with damp; however, be aware that it’s a legal requirement for sellers to disclose issues such as damp to any potential buyers and that failing to do so could have serious legal ramifications.
Who looks at damp in houses?
You may choose to get a survey done by a specialist damp surveyor but will also find that there are companies that specialise in the treatment of rising damp as well as preservation companies who can advise you.