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rising damp |
Rising damp can cause many problems, it is not normally a problem in newer properties as they have a effective physical damp proof course which is either a layer of plastic through which damp cannot pass or a few courses of engineering bricks, which again do not absorb water. Damp houses are bad news this is why mortgage companies insist on doing a survey which checks for a suitable damp proof course. In refurbishment properties you normally have just two choices, either a chemical DPC (damp proof course) or a electrical DPC. Rising damp is not only harmful to the fabric of the building, but it is also harmful to the occupants of the property as damp spores can be inhaled and cause serious health problems.
The chemical DPC works by injecting a chemical (often silicone) into the bricks, the bricks soak up a chemical such as silicone and so become waterproof and so the bricks can no longer soak up water. This method is far from perfect and it will not work in stone, instead the mortar between the joints is injected, which to me seems pointless. Before a DPC is fitted all the plaster needs removing from the wall and this can cause considerable mess!
Electrical damp proof courses ( electro osmosis) is a far better option in my opinion, This has been installed in two of my houses with little work and can easily be done inside half of a day. This system has the advantage that it will work on walls that are up to three feet thick. If the electro osmosis is being installed in walls that are not damp, as a preventative measure then the plaster does not need removing first! if the property has suffered from rising damp then the plaster will have salt contamination which is hygroscopic so you could install electro osmosis to stop the damp rising but the plaster will absorb any moisture in the air and show signs similar to that of rising damp.So the only true way is to install a dpc and re-plaster with a 3 to 1 sand cement with an integral waterproofer/salt retardent.
Rising damp is caused by capillary action, if you take a common house brick and place it in a bowl of water and then mark the level of the water on the brick, then leave it for a day or so you will find that there will be a water mark on the brick that is higher than the mark you made on the brick, this is known as capillary action! Often if you see a flood and look at the brickwork of buildings you will see the level of the flood water and often a damp mark above the flood level, this is not where the water has been at it's highest but is due to capillary action. Not all building materials will absorb the water, but many will.
Does rising damp exist?
There are a few people that have recently said that rising damp does not exist, some of these people have done tests by building small walls and standing them in a vessel with water in the bottom, other people say that it is impossible to detect rising damp with a damp meter!
Personally I take these comments with a pich of salt, I have renovated houses in the past that have clearly had rising damp and once the electro osmosis damp proof course had been installed the problem went away. Most mortgage companies will not lend money on a property that has rising damp and they insist on having a suitable damp proof course fitted. If your mortgage company finds rising damp then it will require treating, regardless of what anyone says about rising damp not existing.
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Electro osmosis damp proof course |
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