Rising Damp Vs Penetrating Damp – The Difference Explained

Many homeowners are confused about rising and penetrating damp, both of which present a very real threat to London homes and a mistaken diagnosis could be costly. In this short article, we aim to add some clarity to the issue, so that you don’t misdiagnose a damp issue in your London home.

What is Rising Damp?

This is a term used to describe moisture that comes up from the ground, hence the name ‘rising damp’. This occurs because of capillary action, as the moisture is drawn into building materials like brickwork and timber and unless it is addressed, the damp will continue to spread through the brickwork and damage the property. Typically, buildings have a damp proof course that is fitted between the lower brickwork courses, which provides a waterproof barrier to prevent moisture passing and rising up the structure.

Damaged Damp Proof Course (DPC)

Rising damp can only occur if the DPC is damaged; it might be split due to ground movement, or it could have degraded over many years, which often happens with older London properties. Another way damp can rise up the side of a building is if an extension is added to the house without a DPC and the brickwork comes over the existing DPC, allowing moisture to make contact with brickwork above the DPC line. Terraced houses are particularly prone to rising damp; all it takes is for one property to be compromised and the damp would spread to the other houses.

What is Penetrating Damp?

This refers to damp that enters a building via the roof or the walls, which penetrates into the interior, causing considerable damage. Basically, if damp does not come from the ground, it is penetrating damp and before repairing any damage, it is important to carry out effective damp-proofing. A common cause of penetrating damp is a leaking roof, while blocked guttering can also lead to rainwater running down the external walls. Damaged masonry is another cause of damp damaging a building and if you suspect that your London home is under attack from damp, book an independent damp survey from London Damp Specialists and find out whether or not your home is being damaged by damp, mould or timber rot.

Independent Damp Survey

At London Damp Specialists, we have been inspecting London homes for many years, providing homeowners with detailed reports that cover every aspect of damp, mould and timber rot. There are different levels of damp survey, depending on your needs, plus we offer an additional plaster lab analysis service where we test up to 10 samples of plaster from various locations in the house.

All forms of damp cause property damage and if you are planning to buy a house in London, we recommend arranging for one of our certified damp surveyors to inspect the building, which will give you an accurate appraisal of the condition of the property, then you can make an informed decision about the purchase.