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Damp Patches On Internal Walls

There are several causes for damp patches appearing on interior walls including damaged guttering, cracked roof tiles and more commonly condensation. Condensation forms when warm moist air within a room touches a cold internal wall or surface.

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Have you recently found damp patches on the walls of your bedroom or living room?

Patches of damp on internal walls are generally the result of penetrating damp, where water from outside gets into the brickwork through gaps and cracks. If the patches are clustered around windows and doors, then it's likely that rain is getting in through gaps around the frames.

Damp can cause serious damage, not only to the appearance of home but to the structure of the property and your health. It can lead to the deterioration of masonry, cause plaster to crumble, wooden beams and floorboards to decay, chimney breasts to crack and leave bubbling on your wallpaper. 

Damp issues stem from poorly ventilated properties, you can usually spot a damp affected area by having cold spots or feeling wet to the touch.  


Unfortunately, inappropriate treatments for damp problems commonly cause more damage and leads to unnecessary expense through the installation of damp proof courses and sealing up walls rather than improve their ability to breathe.

It is important to understand the difference between old buildings and new builds in order to remedy the damp patches that are appearing in your home.

  1. Old buildings are designed in such a way that they must be allowed to breathe.
  2. New builds work on a system of defensive barriers which keep moisture out.

Installing loft and wall insulation in an old building will keep it warm in the winter months but it will also cause your home to sweat which is when problems start to happen and damp patches start to appear on your walls and ceilings.


Whilst insulation is great for making top floor rooms warmer, it comes at the cost of making your loft or roof space cooler. Condensation in lofts occurs when humid air makes its way through insulation or other gaps into the loft space and hits a cooler surface leading to beads of moisture on timbers, lintels and on the underside of the roof.

As a quick tip, if you are looking to re-insulate the loft space to improve the energy efficiency of your property, use thermal insulation with a vapour barrier a vapour barrier fitted on the “warm” side of the insulating material. As with other rooms in the house, condensation in the loft is caused by excess moisture in the air and a lack of adequate air ventilation. Have a look at our top reasons this may occur in the loft:

  • Additional insulation has been laid down in the loft restricting the natural air circulation in the property, meaning lofts stay much colder than the rest of the house, so humid air is more likely to deposit its moisture on surfaces in the loft.
  • Roof vents have been covered or blocked by storage boxes or other items stockpiled in the loft.
  • Hot water tanks releasing steam and moist air into the loft or roof space.
  • Steam from activities such as bathing and cooking combining with a lack of general ventilation to create excessive moisture rising into the loft.



Condensation damp is more commonly found on windows when the warm air circulates around a property and lands on the cold window panes which forms water droplets - condensation.

There are however two other forms of damp that need to ruled out before we can confirm that the dampness inside your house is indeed condensation.

  1. Rising Damp
  2. Penetrating Damp

If the damp patches on your walls appear to rise up from ground level or there is a powdery deposit on wall surfaces close to the floor, then rising damp is probably the culprit. 

Rising damp usually occurs due to a failure or absence of a damp-proof course. It is very unlikely you will suffer from rising damp if you live in a flat above ground level as the damp has to come from the ground level.


How do you treat rising damp?

Improve the drainage of the site where the property is situated. Ensure that the ground surrounding the building is sloping away from your property and then check to make sure there is enough room under your floorboards for moisture to evaporate from the soil below.

Another solution to cure damp on internal walls is to paint walls and ceilings with a mould resistant emulsion paint. The paint adds another damp-proofing element for internal walls agains condensation and helps to prevent unwanted mould growth. 

Another form of damp is penetrating damp. If your interior walls are damp and it seems to be isolated to one area of the wall then it is likely a result of water from outside getting into the brickwork through cracks or gaps in the outside walls.


How do you treat penetrating damp?

Regular maintenance of your external walls should stop the damp from penetrating through in the future. Ensure the pointing and both internal and external paintwork is kept in good condition and make sure you seal the gaps around window and door frames.

If you have ruled out both of the above types of damp and there is no damaged guttering or missing roof tiles then it is more than likely that your property is suffering from condensation.

As we try to make our homes more energy efficient with double glazing, loft insulation and damp proofing we are also making our properties more airtight. This causes moisture to build up indoors and humidity levels to increase which is due to inadequate or indeed a lack of ventilation and over-efficient improvements to our homes.


If it doesn't appear to be rising damp or penetrating damp then those damp patches that suddenly appeared on your interior walls are probably due to condensation. If you are the homeowner or a landlord with several property we can confirm that the problem is indeed condensation by arranging a free home survey where we will visit your property and check the damp patches on your walls.

As the majority of damp patches are actually caused by excess moisture in a property, we have also written a useful guide which offers 14 top tips to reduce condensation problems which you may find helpful.


Need help with condensation, mould or damp problems?

One of our local experts will contact you to learn more about your problems, offer free expert advice and make recommendations for a permanent solution.

During the free survey we will

  • check Assess any condensation, damp or mould problems in your property
  • check Take readings of the relative humidity levels
  • check Identify any underlying problems and make recommendations for a permanent solution

Need help with condensation, mould or damp problems?