Rising damp

Help & Information for Homeowners

What exactly is rising damp?

Rising damp is simply due to the process of external ground water being drawn up through brickwork by what is known as capillary action.

Its presence is normally indicated by moisture at the base of the wall, reducing with increasing height. Often a ‘tide-mark’ is visible. Hygroscopic salts (particularly chlorides/nitrates) are almost invariably present in groundwater and will therefore be found in walls and plaster suffering from rising damp.

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Why has rising damp affected my property?

There could be a variety of issues that may have led to the occurrence of rising damp within your property. Without a proper investigation (ideally with a qualified damp specialist) it is impossible to advise what the exact cause of your issue is. That being said, there are some common causes of rising dampness. These can include:

Moisture by-passing over the damp proof course with higher ground levels around the base of the property, eg. installation of patio a planting area
Failure of certain types of damp proof courses
Incorrect installation of the damp proof course when a property was constructed

Rising damp explained >>

Rising damp on internal wall - Property Care Association

What exactly is a damp proof course?

A Damp Proof Course (or DPC) is a waterproof barrier installed roughly at about 6 inches from the ground around your property or buildings. It is there to prevent capillary climb of water through the brickwork or masonry and up walls.

Over time, the material used as a damp proof course has changed with some early types including overlapping slate, lead and engineering bricks. Today the vast majority of DPCs are constructed of Polyethylene, these are highly reliable and have proven incredibly robust.

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Is rising damp a serious problem?

In terms of how serious an issue rising damp is, if left untreated, it can damage your walls and ruin decorative finishes. This damage typically takes the form of damp tide marks and deposited salts on the wall. It can also lead to timber decay issues such as wet rot,(possibly even dry rot if there is enough water/moisture) and can lead to greater heat loss due to the increased conductivity of the walls

How you can spot rising damp?

Decayed skirting boards, crumbling or salt stained plaster, discolouration and staining, decayed timber floors, peeling paint and wallpaper are all common when walls are affected by rising damp. Most types of masonry used in the walls of buildings will allow some water movement by capillary action; however, this is usually controlled by a physical barrier or damp proof course. If this physical barrier is absent, has broken down or is damaged then it is often possible to install a remedial damp proof course (DPC) to control water rising from the ground.

Water rising from the ground often introduces contaminating salts into the walls and plaster coats. This contamination will often result in a need for the plaster to be removed and replaced using specially formulated salt resistant plasters.

What does rising damp look like >>

What you can do to resolve the rising damp?

If rising damp is suspected, it is important that it is corrected & investigated further. We would always recommend that the surveyor who undertakes investigations is suitably trained, experienced and qualified with the CSTDB qualification.

Where the cause of rising damp is due to the bridging over the damp proof course, i.e. raised ground levels, bridging plaster render, or debris in the cavity; then removing the ‘bridge’ should hopefully be sufficient to control the capillary rise of moisture in the wall.

However, if it is the case that the damp proof course has failed in some way, then we would suggest you speak to one of our local PCA qualified damp specialist and to potentially organise a survey. The survey will be able to provide suitable guidance dependent on the cause of the dampness and the nature of your property

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Find a qualified damp specialist near you

The Property Care Association (PCA®) is the trade body representing specialists across the UK who can be trusted to help resolve problems affecting buildings such as rising damp

All PCA members have to meet strict membership criteria to demonstrate their technical competence and service delivery standards. To find a PCA specialist near you, simply enter your postcode below and search for a qualified and trusted PCA specialist near you.

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Professional Damp Guidance

For professional tradesmen or contractors looking to find out more technical detail about penetrating damp and other forms of dampness, visit our professional guidance section.

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