Spotlight on damp
If you’ve ever had a damp problem in your home, then you’ll know how distressing it can be – from condensation and mould to cracked walls, rotting timber and crumbling bricks.
It’s a little-known fact that around 80% of all issues in properties are down to damp, and we’re all susceptible, no matter the size and shape of our home – so it’s important to understand the different kinds of moisture that may be present in your flat or house, how it gets there, the type of issues it can cause and how to manage it effectively.
As a Chartered Surveyor, I like to be aware of best practise when it comes to dealing with damp so I can always be on the lookout for issues and concerns. With this in mind, I recently did a CPD course with the damp specialist, professor and surveyor John Edwards, and I’m pleased to share some of my learning with you good people in this blog.
What is damp?
‘Damp’ can mean different things to different people.
I think of it as the unwanted presence of moisture from the air or ground that’s been prevented from passing through and away from your home, and therefore becomes trapped.
Why does it matter?
When left unmanaged and untreated, damp and moisture can cause serious and costly damage to a building’s infrastructure – from windows and walls to ceilings and floors. What’s more, according to the NHS, if you have mould caused by damp in your home you could be more susceptible to respiratory problems, allergies or asthma.
The prolonged presence of excessive damp and mould can also exacerbate issues that affect our immune system and leave us feeling tired and lethargic, so if you have a damp issue it’s well worth getting it seen to for your financial, physical and emotional wellbeing.
Where is damp usually found?
Moisture is present nearly everywhere and although damp can appear virtually anywhere, it’s most commonly found in or near:
Basements and cellars
Bathrooms and kitchens
Flat roofs
Pipes and guttering
Cavity walls
Masonry and mortar joints
Timber floors
The different types of damp
Condensation: everyday activities like showering, cooking and drying clothes release warm moisture into the air inside our homes. Condensation occurs when this warm air collides with cold surfaces such as windows and walls – leading to water droplets and mould.
Rising damp: caused by water in the ground moving up through a wall or floor, rising damp commonly leads to wet stains and tide marks on walls, skirting boards or stonework. Installing a waterproof barrier such as a damp-proof course in a wall or membrane under a concrete slab can help to seal a house and protect it from rising ground water. Rising damp can be easily misdiagnosed, so remember to pick your experts carefully.
Penetrating damp: this happens when moisture enters a building through the fabric of the walls. It can be caused by broken pipes and gutters, construction issues or raised ground levels and is often identified by watermarked masonry.
Leaks: generally, leaks will be isolated to one particular area or wall. If you notice specific damp patches at home, identify any nearby water sources that might be leaking and have them seen to by a qualified plumber.
Some treatments, tips and solutions
Different damp problems require different treatments, so it’s essential to correctly diagnose the specific cause of your particular issue, rather than just dealing with the symptoms. A RICS Home Survey will help identify problems before you purchase a property, and you may also need a damp specialist to advise on a remedial course of action depending on the extent of the problem.
Become aware of your home’s general use and its internal and external environment: understanding the way moisture moves through the house (or not!) and which walls are more vulnerable to rain can help you nip any issues in the bud. Good ongoing maintenance is also very important.
If you regularly dry clothes indoors, open windows to enhance ventilation or consider buying a dehumidifier to draw excess moisture out of the air.
Installing extractor fans in bathrooms and kitchens is a simple and relatively affordable way to improve airflow and reduce condensation – remember that bathroom doors tend to need to be kept closed for the fan to run. The Home Ventilation Institute (HVI) recommend that fans should run for at least 20 minutes after showers have been used, which can be helped by installing a fan with a timer switch. Also keep in mind that many older properties have fans which are not ducted to the outside, which can actually contribute to the problem.
If you suspect your walls are damp, check your external gutters and downpipes: cracks and clutter from dead leaves can lead to poor drainage and cause water to leak through walls. There will be staining on the outside of the wall if the gutters or down pipes have leaked or overflowed for a period of time.
If you’re having work done at home, always ask around for recommended tradespeople. Over the years, I’ve seen too many examples of jobs being done without enough care or attention, which often leads to damp problems later down the line. One example is when mortar is accidentally dropped in the space between cavity walls, forming a bridge through which moisture can cross.
Always consider the construction type and age of your home. Modern and traditional buildings are built using different materials and methods, and they need to be treated accordingly. For example, the application of a modern cement render to the walls of an old property can lead to problems, because it creates an impermeable barrier through which any trapped moisture cannot escape and so it gets driven into the property. You can think of it a bit like wearing an anorak on a hot day… never a good idea!
Older bricks can become porous and allow water into your home, so they may need to be replaced. In some cases, a damp-proof paint may do the trick and seal walls up again, but you need to use ‘breathable paint’ – a coating that can allow water toevaporate from the surface, preventing it from accumulating in the building’s fabric. However, it’s always a good idea to seek professional advice on what would work best for your home’s age and construction: there is currently no defined standard for ‘breathable paints’ and a lot of conventional masonry paints don’t have the right level of moisture resistance, making the transfer of moisture to the atmosphere difficult if not impossible.
One of the most common problems is the use of cement mortar to repoint brickwork on older properties such as Victorian homes, where lime mortar was originally used. Cement mortar doesn’t allow bricks to breath, and this results in the face of the brick deteriorating due to trapped moisture which freezes during winter, meaning moisture gets driven inside the property.
Each week, I notice older buildings having newer building methods or materials applied to them, such as open fireplaces being closed up and single glazing being replaced with double. This actually seals an old building up, decreases ventilation and in a worst-case scenario, can actually affect the structural integrity if moisture gets into joists, floorboards or weight-bearing timber. Thankfully, I’ve never seen anything that dangerous, but I do see cases moving in that direction all the time.
Finally, a friendly cautionary word on ‘free’ damp surveys. Bear in mind that often these surveys are carried out with a view to selling a damp system – which may not actually get to the root of the problem but only treat the symptom/s – so there is a slight conflict of interest here. In my opinion, if you have a serious damp problem, it’s always better to pay for an independent and specialist damp surveyor if you can.
Although no standards currently exist on safe indoor levels of damp or mould, I understand that RICS – the Royal Institution of Chartered Surveyors – is soon to publish guidance specifically on damp and I’ll be sure to share this on my blog once available.
I hope this has been a helpful read, but if you’ve got any questions or want to ask about a survey, feel free to drop me an email today at roo@rmsurveyors.co.uk.
Warm wishes,
Roo
