FEATURES - Rising Damp
THE SYMPTOMS AND SIDE EFFECTS OF DAMP
In order to correctly identify the origin of damp within a building, the surveyor must be aware of all the possible sources of damp, 
No D.P.C or existing D.P.C
ineffectiveas well as the underlying effects of this damp to the building and its occupants. This information would be required to ensure that the correct and appropriate remedial measures are carried out onthe property. There are several elements responsible for the appearance and development of damp in buildings. Most of these are bought about due to the absence or ineffectiveness of the buildings existing Damp Proof Course (DPC), but a variety of other factors can also contribute to this problem, resulting in the overall damage of the property and its contents.
The life style of the occupants in a property can have an immediate effect on the buildings humidity, by controlling the amount of heating, ventilation and insulation, they are working to influence the levels of condensation. If the levels of condensation are significantly increased, moisture begins to collect within the buildings structure, enabling the damp to spread throughout the property.
Pointing unsuitableDefects found in the buildings roof, walls or plumbing will also permit damage to the building, by causing a penetrating dampness and faults in the DPC at ground level, resulting in the presence of rising damp. If the damage is left untreated, a catalyst of other problems are then exposed to the building and its occupants, which can lead to unhygenic living conditions and structural damage to the property. Below are some examples of the damaging effects that can arise from the presence of this damp.
- The increased moisture content in timber can produce suitable breeding conditions for a variety of fungal decay.
- Most insulation is rendered ineffective when in direct contact with water or damp.
- Mortar and brickwork deteriorate and cause the spoiling of plaster and decorations.
- Electrical short-circuiting can occur, causing a major safety hazard to the property and it's occupants.
- Mould growth and development is encouraged by high levels of condensation, causing possible health risks to all of the occupants.
HOW DOES A DAMP PROOF COURSE IMPROVE A BUILDINGS RESISTANCE TO DAMP AND MOISTURE?
RenderMost buildings consist of materials that are porous to some extent and thus have the ability to absorb moisture. When a wall is built in direct contact with the ground, the soil (which has a high moisture content), will allow water to soak up into the wall, causing the appearance of damp. The water moves up the wall mainly in the mortar through the capillary, then evaporates at the surface of the wall and into the atmosphere. With the drying action of the air on the upper part of the wall, the water continues to move up the wall, to act as a wick. The height to which this dampness occurs is detemined by a number of contributing factors, although it rarely exceeds 1 metre above ground level. These factors include:
- The supply of water to the structure.
- The wall's thickness.
- Original materials of construction.
- Presence of impervious renderings.
- Rate of evaporation (determined by the temperature).
High ground or path
The function of a DPC in a wall, is to provide a barrier within the wall which prevents the movement of water. Traditionally, blue engineering bricks and slates were used to form the DPC in a wall, but in today's modern construction, a varied amount of other materials are used.
Debris in cavityIt was not until the Public Health Act of 1875, that the incorporation of a DPC became more common and so in many of the older buildings, DPC's were not installed. Even the older buildings that were originally built with a DPC present in the construction, have proved unsatisfactory in combating moisture and damp, because they were either ineffective when laid, or have simply deteriorated with age. Alternatively, the DPC may also have been accidentally bridged and rendered ineffectively by high outside ground levels, or by internal floor screeds.
Solid floor bridging D.P.C ( 1 )
Solid floor bridging D.P.C ( 2 )
I hope that this information, along with the diagrams, has made it easier to understand - not only the importance of having a company like ABS to carry out the work on your property - but also the urgent need to prevent further property defects and expense by isolating the problem in advance. Should you have any further questions, please do not hesitate to ask, as we will be only too pleased to assist you.