REDUCING HIGH GROUND LEVELS IN SOUTH LONDON AND THE HOME COUNTIES
If you have rising damp then it can indicate problems with the damp proof course (DPC) such as bridging of the DPC or failure. In this instance it might be necessary to install a chemical damp proof course.
In a brick or stone wall the materials used act like a sponge and soak up water from the ground.This water is able to rise up the wall due to hygroscopic action and will damage plaster and decorations. In order to prevent this, when a brick or stone wall is being built, a waterproof membrane is inserted six inches or a foot or so above ground level. This acts as a barrier and stops water rising any further.
The presence of rising damp means that this Damp Proof Course (DPC) has failed in some way and remedial action is necessary
No Damp Proof Course to start with!- Older brick and stone built homes may have been built with no Damp Proof Course.
The incorrect installation of a DPC- You will be supprised to know that we even deal with new builds where the developer/ contractor has put the DPC in at the wrong height.
Bridged Damp Proof Course- This can occur for a number of reasons but one of the most common is piling up earth or other materials against the wall outside the house, for example in a flowerbed. This allows water from the pile to seep into the wall above the DPC and rise up the wall. The remedy is to simply remove the soil/debris which will allow the wall to dry out naturally. Other ways in which a DPC can be bridged are within the cavity of the wall.
High Ground Levels- By far the most common type of bridging to a DPC that we at ATRUSS PRESERVATION find is through block paving and crazy paving. Over the years previous owners have laid new paths /paving over the old original ones - thus bringing the current ground level above the original Damp Proof Course.
If your property has an airbrick near the ground level then check to see that the ground level is not higher than the bottom of the airbrick. If the ground level is higher then chances are that the dpc has been bridged, dependant on how long the dpc has been bridged will determine any remeedial works in the future. It may be necessay to remove the defective plaster and install a new dpc or it could be as simple as reducing the high ground levels in the form of a French Drain this it is higher
Sometime debris such as cement or mortar can fall to the bottom of the cavity and create a path over the DPC for moisture, the remedy here is to locate the debris and remove it. If the site is not immediately apparent due to a localised damp patch it may be worth taking advice from a professional.
If you are laying a path or patio next to the house ensure you allow sufficient height between the new surface and the DPC, ensure you check your local building regulations or take appropriate advice on this otherwise you run the risk of damp during heavy rain conditions.
Finally, external wall coatings can bridge the DPC so ensure that any cement renedering or coating such as pebbledash or a Tyrolean finish does not extend below DPC level.
Failed DPC - The Damp Proof Course may have failed due to incorrect installation, ageing or use of incorrect or sub-standard materials.
In most cases the original DPC is level with the bottom of the airbrick.
LONDONS NUMBER 1 CONTRACTOR IN REDUCING HIGH GROUND LEVELS
Should you require a no obligation quotation on damp at your property please contact us now on 07984 712 428 or alternatively please fill in our enquiry form where we will contact you back regarding a survey.
Areas covered include but not limited to London Boroughs such as: Sutton, Wandsworth, Lambeth, Fulham, Lewisham, South Croydon, Southwark, Kingston, Banstead & Reigate, Richmond.
www.moneysavingexpert.com 18 July 2007