Damp: Identifying & Treating the Key Types of Household Damp

Anyone familiar with property programmes on TV will no doubt have heard of damp in the home, and it is a common issue that crops up in building surveys. However, if correctly identified and treated damp can be removed and, ideally, prevented.

The three most common types of damp are condensation, rising damp and penetrating damp. Each of these has different causes and require a different method of treatment to solve the problem.


Damp - Condensation

Condensation occurs when the air outside is colder than the air inside. The inside air condenses and forms droplets which are often seen on walls and/or windows. The amount of moisture in a room impacts on the likelihood of condensation forming; the more moisture a room has, the more likely it is that condensation will form. As a result, condensation is often seen in kitchens, bathrooms, rooms where people sleep, and rooms in which laundry is drying.

Other signs of condensation can include a dark mould often around window openings, water droplets on window panes and streak mark on walls. If condensation is not treated it can result in damage to paint work, plaster and window frames. The mould which commonly grows as a result is harmful to respiratory health.

It is best to try and prevent condensation in the first place by ensuring adequate ventilation to your entire house.

Ventilation ideas:

  • Many modern houses have trickle vents at the top of windows which can be opened or closed. Having the trickle vents open allows a small amount of background ventilation throughout the property.
  • Modern windows often allow the user to lock the window in such a way that a crack of air is able to come in – this will, again, allow background ventilation whilst allowing you to safely lock up your home.
  • Having – and regularly using – extractor fans in kitchens and bathrooms when these rooms are in use makes a big difference. Continue to run the fan for at least five minutes after finishing cooking/bathing and make sure all the noticeable vapour in the air/on mirrors/windows has also cleared up. Bathrooms or en suites that do not have external windows but have a shower and/or bath in may benefit from installation of a continuous fan. This will constantly work at a reduced speed and low volume in the background to reduce moisture, and will then increase its speed and volume when the light is switched on.

Another way to try and avoid condensation dampness forming is to avoid extremes of temperature variation within your house. In winter it may be beneficial to set your heating at a lower temperature constantly or, for example, set at 18 degrees C when you?re in the house during the day and 15 degrees C at night or when the house is unoccupied. This may help prevent condensation forming rather than turning the heating off completely for long periods of the night and/or day and then having it on high for a few hours a day.

If you do have an issue with condensation then it is important to wipe away the water droplets as they form. Using a dehumidifier, in combination with the above tips, may also help reduce the issue. If you are unsure of how to proceed or of the extent of the damp, then an RICS accredited chartered building surveyor can conduct a damp inspection to uncover all issues involved and suggest a suitable course of action.

Rising Damp

Rising Damp is when water transfers into the building fabric from the ground and is more common in older homes built before 1875. At this time regulations were introduced which meant that a damp proof course and damp proof membrane needed to be included with every house built in the UK to provide a water-proof seal at ground level to stop water from seeping in. If rising damp is evident in houses built after this time, it is likely to indicate an issue with one or both of these items.

Key signs of rising damp include; staining to paintwork, peeling or blistering paintwork, tide marks on the wall, damaged skirting boards and a musty odour. This is a serious form of damp and it is important to consult an RICS registered chartered building surveyor to establish the cause of the damp and a suitable solution.

Things homeowners can do to help prevent rising damp include:

  • Before purchasing a house find out if it has a damp proof course and membrane; if your house has had a chemically injected damp proof membrane it is important to check the effectiveness of this and establish whether an insurance backed guarantee is included.
  • Ensure that the level of garden soil directly next to the house does not rise higher than the level of the damp-proof barriers.
  • Ensure that rainwater goods are well designed and maintained and are not allowed to saturate the ground.

In older homes that do not have damp-proof courses or have less substantial ones, modern renovations such as plastering or insulation may exacerbate any damp issues by reducing the natural ventilation of the building.

Treating rising damp may include repairing the existing damp-proof courses, installing a new damp-proof course or, for less serious instances, increasing the ventilation to the home (see suggestions for treating condensation above).

Penetrating Damp

Penetrating damp refers to any water that leaks through the wall, roof or ceiling; this type of damp spreads horizontally. Penetrating damp can be caused by leaks in the exterior of a property or plumbing issues.

Typical causes include:

  • Leaking roofs: tiles may be loose or broken; the flashing may be damaged.
  • Overflowing gutters: they may have come loose or be blocked with leaves or debris.
  • Leaking downpipes.
  • Damaged or deteriorated exterior walls: there may be cracks or damage to the pointing, cladding, render or pebbledash.
  • Poorly fitting doors or windows.
  • Leaking interior pipes.

Penetrating Damp

Common signs of penetrating damp include: damp patches (that often look like a brown stain) suddenly appearing on an interior wall, ceiling or near a chimney breast; wet and crumbly plaster; large bubbles appearing in the plaster (which can lead to holes in the ceiling if left untreated).

To treat penetrating damp it is important to identify the source of the leak and make appropriate repairs to fix the issue. An RICS accredited building surveyor will be able to conduct a damp inspection to help you identify the source of the leak and how to best treat it. If you live in a flat then it is worth chatting to your neighbours to see if they are experiencing similar issues which may help highlight the cause.

Keeping your home well maintained and quickly repairing any issues both externally and internally is the best way to prevent this type of damp.

  • Regularly check roofs by looking in the roof space for any signs of water coming in or any timbers that feel wet.
  • Ensure that air bricks and other ventilation/moisture preventing devices (eg. damp-proof courses) are not obstructed to allow proper ventilation of the home.
  • Make sure that exterior pointing and paint work are properly applied and well maintained.

If you are concerned about damp in your home contact usto organise a damp inspection.

Please note:this information is intended for general information purposes and should not be seen as professional advice. It is important to talk directly to an RICS accredited Building Surveyor and/or Architectural Designer to discuss your individual circumstances.


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