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What Kind of Damp is Affecting my Home?

Date posted: 13 December 2016

When you discover a damp problem in your home it is important to establish what type of damp it is that you are dealing with so that you can work out how to tackle it effectively – without wasting money on solutions that simply won't help.

You can make use of Google's image search to find photographic examples to help you identify the type(s) of damp in your home. You will also be able to find information about possible causes, and what you can do to eradicate the problem.

Three of the most common types of damp suffered by British householders are:

  1. condensation;
  2. rising damp; and
  3. penetrating damp

All three types of damp need to be treated as quickly as possible before the problem worsens. Left untreated, damp creates unhealthy living conditions – encouraging mould growth, for example, which is associated with a whole host of health issues. On top of this, damp can cause expensive damage to your property.

Each type of damp must be treated in a different way, however, and the cost of doing so can vary significantly – so it is crucial that you establish exactly which types of damp are affecting your home before you spend money trying to resolve it.  


Condensation is the most common kind of damp, particularly during the winter, often causing streaming windows or damp patches on internal walls. It occurs when moist air meets cool surfaces, and is often a problem in rooms that generate lots of air moisture such as bathrooms and kitchens. 

Poor ventilation, and heating that switches on and off regularly, can make the problem worse because these conditions enable warm, damp air to condense. 

Older homes – which once had natural ventilation via chimneys, and single-glazed wooden framed windows – may suffer worse condensation if chimneys are removed or air-tight double glazing is installed.

Signs of condensation include:

  • water droplets on windows and/or walls;
  • dark mould on windowpanes or around the edge of windows; and
  • an unpleasant smell.

Left untreated condensation may damage plaster and paintwork and cause window frames to rot. 

To help alleviate condensation problems:

  • wipe down any condensation from windows;
  • open the window whilst carrying out activities that naturally generate moisture in the air (such as cooking and showering); 
  • look at ways to improve your home's ventilation; and
  • invest in a portable dehumidifier for use in the rooms that need suffer the most condensation.

Rising damp

When ground water moves up through a wall or floor it causes rising damp. This can be prevented from happening by the installation of a barrier:

  • a damp-proof course is a horizontal strip, often made from plastic or bitumen felt, that is installed in the wall at least 15cm above ground level
  • a damp-proof membrane is a sheet of material laid under the concrete floor that does not allow water through it. 

The damp proof membrane should be linked to the damp-proof course so that the house is properly sealed.

Modern homes will have been built with both of these in place thanks to building regulations, but older buildings (particularly those built before 1875) may well not, or they may have been damaged over the years. Rising damp can also occur if the ground level outside your property is higher than your damp-proof course, or if there is inadequate drainage which allows water to get above it. 

Signs of rising damp

You may spot rising damp in the form of damaged skirting boards or plaster work, peeling paint and wallpaper and wet patches on the walls. Rising damp may dissolve soluble salts from the ground and building materials, which in turn can crystallise, creating a white powdery substance. In combination with the water this may leave an unsightly tide mark running along your wall.  If the problem is rising from the floor the carpets or other floor coverings may start to lift, or you may feel damp patches.

Solving the problem of rising damp 

Unfortunately rising damp can be an expensive problem to fix, and you may need to call in a specialist damp company. If you own an older property you may need to have a damp course installed. If there is one already in place, but you are still seeing signs of rising damp, the chances are it has been damaged. Where rising damp is extensive you may need to have the entire damp proof membrane replaced, but if there is only a small patch of damp you may be able to prevent more moisture coming through by painting over the area with two coats of bitumen latex waterproof emulsion underneath the floor covering (available from DIY shops). 

Penetrating damp

When water leaks through walls it is called penetrating damp, and it will expand horizontally across walls or ceilings rather than travelling vertically (as with rising damp).

Structural problems are usually the cause of this problem, including a leaky roof, broken guttering or cracks in the walls. This allows roofs or walls to get saturated with water regularly. Another possible cause is an internal leak such as water pipes beneath a bath or sink. 

Signs of penetrating damp 

You may spot damp patches on your walls or ceilings, which in the case of external leaks will worsen when it rains heavily. Older building designed with solid walls are more prone to penetrating damp, because modern cavity walls offer some protection from this.  

Solving the problem of penetrating damp

Your first task will be to work out what is causing your penetrating damp. This will involve a thorough inspection of the exterior of your property for leaky gutters or downpipes, loose or missing roof tiles, or any other issues that could cause walls to become saturated in places. Check the pointing (i.e. the cement between tiles), the flashing (i.e. where the roof meets the wall of a chimney) and your roof ridge tiles (i.e. the triangular-shaped tiles on the very top of your roof). If any are missing or loose they will need fixing down or re-pointing. Take a look at your window frames to see if there are any gaps around them that could be letting water in. You may be able to fill gaps or cracks yourself with flexible frame sealant from a DIY store. Check under your windows for a 'drip groove' (designed to prevent water going onto the wall) and, if there is one, ensure it is not filled in. If there is not drip groove you could Google how to add a hardwood strip yourself to see if this helps sort out the problem. Inspect the walls and door frames for cracks that may need repairing. You will also need to check for leaky water pipes inside your home, particularly in the bathroom and kitchen. 

If you can find the source of the problem you may well be able to fix things yourself, but if not you may need to call in damp specialists.

Damp proofing tools for the Job

At Best at hire, we offer an extensive range of damp proofing tools and drying equipment including air movers and dehumidifiers for hire which can help with fixing damp and condensation issues. Call one of our experts to discuss your requirements today. 



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