Damp Proofing General Information:
Rising damp is caused by water migrating through the capillaries of materials that most buildings in the UK are constructed from. This is primarily stone, brick or other regional methods of construction, together with the materials which are used to bond the substrates together, e.g. mortar, which can be various types, lime, sand and cement, ash, together with various other materials which have used throughout the centuries. Water can travel through these capillaries to a height which will be determined by how narrow the capillary tube is. The narrower the capillary tube, the greater the height reached. To overcome this problem in new construction, a physical damp proof course is installed at least 150mm up from the external ground level. This prevents the rise of water within the wall by breaking the continuity of the capillary action.
In some situations, the damp proof course can be totally missing, broken down over a period of time, or has simply been breached, allowing moisture to rise up the wall through capillary rise, i.e. rising damp. Rising damp causes damage to interior plasterwork and can soil decorations. It shows itself by causing wallpaper to peel and paint to blister. These problems are often made worse by the appearance of efflorescing salts on the surface of the wall. These salts, if deliquescent or hygroscopic can make matter worse as they will extract moisture from the air into the problem of surface dampness.
The physical deterioration caused by rising damp, and the costs involved in remedial work are problems enough by we should also bear in mind that a cold damp property is an unhealthy environment and is also expensive to heat. These problems can be further aggravated as rising damp is often the cause for other associated defects such as dry and wet rot, which once established, can spread over a wide are and can be both destructive and expensive to eradicate.
Penetrating damp can be as a result of a wide variety of causes e.g. building defects, such as cracked and defective external rendering, damaged and defective rainwater goods, i.e. downpipes and gutterings, leaking roofs, high external ground levels and badly fitted or rotten joinery.
The penetration of moisture through external walls at low level can often be confused with rising damp and care must be taken during an inspection to accurately identify all building defects that may be contributing to dampness within the property. Again wet and dry rot attacks are often instigated by external defects, allowing water to penetrate the fabric of the building.
Hygroscopic salts are a symptom of rising damp and have the ability to trap moisture and will also be present following damp proofing treatment, e.g. the new damp proof course which has been installed. These salts will remain unless they are also treated as a separate problem. They are often the result of rising damp and on completion of damp proofing treatments in the property, the moisture which is already above the level of the new damp proof course will in time evaporate, but whilst this process occurs, salts in the fabric of the structure will be carried to the surface of the wall at times of high humidity.
There are various chemical types of salts which come from different sources such as unwashed building sand, contaminated masonry and substrate from agricultural buildings that have been converted into living accommodation. There are also salts within the ground. Existing plasterwork which is contaminated with salt must be removed in conjunction with damp proofing treatments and this is the reason why replastering is always necessary upon completion of damp proofing treatment.
Condensation & Mould
Anchor Property Care cater for and install a wide range of mechanical and automatic ventilation systems, fans, etc for a wide range of buildings and properties. Our surveying and design team are able to assess the most efficient method of ventilation for your property.
The installation of a new damp proof course is designed to create a continuous barrier throughout the length and width of the wall to reduce the capillary rise of moisture. More common methods of damp proofing treatments used by Anchor Property Care are as follows:
Aqueous based silicone fluid is injected under pressure, having the effect of reversing the meniscus in porous masonry. Once inserted, the siliconate prevents moisture from rising within the capillaries, creating a new damp proof course.
This is the very latest in damp proofing technology utilising a concentrated emulsion cream for the control of rising damp. The cream is delivered by hand pressure only and migrates rapidly into the masonry pores.
The use of electro-osmosis has particular advantages in stone walls of greater thickness. The system introduces a very small and perfectly safe electrical current into the wall just above ground level. Its effect is to repel the rising moisture molecules down the wall and harmlessly back into the ground.
The mortar injection method uses a specially formulated dry mix of cement, quartz and reactive chemicals. Once mixed with water, the chemicals released react to form a crystalline growth, which penetrates and blocks the capillaries, pores and fine cracks within the mortar.