What is Rising Damp and where does it occur?
Rising damp is where moisture from the ground moves upward into the structure by what known as capillary action. This becomes apparent in the lower parts of the wall above the skirting level.
The moisture effectively dissolves salts from the wall construction which are then drawn to the surface of the walls. When the moisture subsequently evaporates this leaves behind salt deposits which are known as ‘efflorescence’.
In addition this excess moisture within the property can lead to condensation, where the moisture evaporates into the air only to condense on the walls, windows and in other locations when the temperature drops.
The damaging effects of dampness in the structure and on the surface can lead to the decay of timber joists and skirtings from dry rot, wet rot and timber infestation by woodworm.
The continual damp conditions if not treated will lead to the growth of mould causing further damage to the structure.
Properties that were constructed before the use of the cavity wall method, quite often had solid walls where a damp proof membrane (DPC) was not installed, something that is fundamental in modern construction.
What can you do to resolve the issue fo Rising Damp?
How do we go about getting this done?
Well, we need to introduce a moisture barrier into the structure. The most common method is where specialists inject a chemical solution into the wall by drilling holes at a specified distance apart and approximately 150-175mm above the outside ground level. They then inject a solution in each hole that creates a uniform barrier within the wall.
Once you’ve addressed the issue of moisture rising into the walls, you need to have a look at the internal render and plaster skim.
Due to the salts being drawn out of the structure, it’s highly likely that the internal render and plaster will have been affected. So, it will be necessary to hack off the internal plaster, usually to a height of 1 metre.
Once the DPC has been installed, always give the wall some time to dry out. Once completely dry, it can be re-rendered usually with a waterproofer and then skimmed flush to match the wall.
The specialist will provide you with a guarantee provided by the manufacturer of the Damp Proof products. It is underwritten on the basis that the installer has undertaken the work in accordance with their instructions.
When you come to sell your house or project the purchaser’s solicitor will ask for the guarantee if you state that you have had this work done.
Are there other methods that can be used to resolve Rising Damp?
An alternative to the liquid injection method is a physical DPC membrane. This plastic membrane is supplied in rolls 100-600mm wide. This method will involve removing sections of the wall to install the DPC. This can be very labour intensive and expensive but it is a more thorough method than the liquid injection.
Still not sure? Get in touch.
If you have any questions about rising damp or other issues, please don’t hesitate to get in touch.
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Thanks for reading.
Mike Woods, MCIAT
