Damp is a common problem, but many aren’t aware of all the various reasons why damp could be occurring in their home. Rising damp, penetrating damp and condensation are the three most common types of damp in residential properties.
Each needs to be treated differently, and damp repair costs can vary dramatically, so it's important to know what type of damp is affecting your home before you try to get it fixed.
As with many things, the worse the situation gets, the more it's likely to cost to eliminate and repair any damage. To familiarise yourself with these issues, keep reading and know what you’re dealing with!
Types of damp
Condensation in homes generally occurs when moist air comes into contact with cool walls. You may notice that this is particularly common in rooms that naturally generate a lot of air moisture, such as kitchens and bathrooms. It is often more prominent in the winter months of the year, as walls tend to be colder than the air inside.
Condensation can be exacerbated by central heating, as it can get very warm and then cool down again, which in turn creates warm damp air that can damage your home.
Poor ventilation is also a factor. This can be particularly apparent in old homes, as they were originally designed to allow damp air to evaporate out of the house. This was great once upon a time, but the removal of chimneys, air bricks and installation of energy-saving measures, such as air-tight double glazing, have reduced ventilation in some old homes.
Here are some of the symptoms of condensation to look out for:
· Water droplets and staining on windows, ceilings or walls
· The appearance of black spot mould, particularly on glass or around windows
· An unpleasant mouldy smell
If left untreated, condensation can damage paint and plaster and cause window frames to decay. Health issues can also occur. To keep it at bay, when you see it forming, you can wipe it away with a cloth. If you'd rather use less elbow grease, there are certain gadgets available that can help with condensation and leave your windows streak-free.
If you think the problem is a lack of ventilation, there are systems available to help improve it. If the condensation is occurring in the bathroom specifically, opening of windows, use of a mechanical extraction fan and keeping heating at a lower constant temperature can assist. Dehumidifiers can also come in handy to reduce how much moisture is in the air in the first place.
Rising damp is caused by water from the ground moving up through a wall or floor. It's natural for walls and floors to let some water pass through. However, a barrier called a damp-proof course or damp-proof membrane usually prevents it from causing any damage.
A damp-proof course is a waterproof horizontal strip, typically crafted from plastic or bitumen, with slate used in early cavity walls. The damp proof course is built into the wall at a height of at least 150mm above ground level.
A damp-proof membrane is a sheet of material that's impervious to water, which is laid underneath the floor during construction. This is then connected to the damp-proof course in order to effectively seal and protect the house from ground water.
Newer homes should have both, as they are a requirement of building regulations. Older buildings however, mainly those built before regulations came into force, may not. You may even have these barriers installed, but over time they could get damaged or worn out. If this is the case, your walls or floor could end up suffering from rising damp, if not already.
Rising damp may also occur when drainage is poor or there is none whatsoever. Or perhaps if the level of the ground outside your home is higher than your damp-proof course, which in turn will allow water to flow above and past it. This situation could also be referred to as penetrating damp.
Here are some symptoms of rising damp:
· Damaged skirting boards or plaster
· Peeling paint and wallpaper, often with wet patches
· A white, powder-like substance on the wall, left by soluble salts dissolved in the water
· Tide marks rising up the wall
· Floor coverings lifting up.
The third most common type of damp is known as penetrating damp, and is caused by water leaking through walls. This kind of damp can expand across your walls and ceiling. The way to tell if it is penetrating damp, is that it will typically move horizontally, rather than by travelling vertically up walls (as is the case with rising damp).
Penetrating damp is typically caused by a lack of maintenance to a building, such as faulty guttering or roofing, or cracks in the walls. These defects will let water soak through, saturating the wall surfaces during heavy rainfall. It can also be caused by internal leaks, such as leaky pipes underneath the sink or bath.
You’re more likely to get penetrating damp if you live in an older building with solid walls, as newer cavity walls provide some protection.
The biggest symptom of penetrating damp are damp patches on the walls and/or ceilings. Look out for these patches darkening when it rains.