Dampness can occur for a number of reasons but is typically as a result of one of four areas, condensation dampness, rising dampness, penetrating dampness and leaks. Compared to modern buildings, older properties were not specifically designed to stop damp problems by preventing the excess build-up of moisture. The reason for this is that older properties were built entirely from permeable materials with no attempt at waterproofing, unlike the construction of modern buildings.
Dampness in properties is one of the most frequent problems encountered by property owners in the UK. It is essential that the correct diagnosis is provided and only the necessary solutions are used to stop the damp problems affecting your property.
There is always some moisture in the air, even if you cannot see it. If the air gets colder, it cannot hold all the moisture and tiny droplets of moisture appear. This is known as Condensation. It appears on cold surfaces and in places where there is little movement of air (eg: In corners, on/near windows, behind wardrobes) Mould growth is associated with condensation and can be found on damp surfaces such as plaster, wallpaper and timber
There are steps you can take to reduce Condensation
PRODUCE LESS MOISTURE
1. Cover Pans
2. Dry washing outdoors
3. Vent tumble dryers to the outside
VENTILATE TO REMOVE MOISTURE
1. Keep a window ajar or a trickle ventilator open
2. Ventilate kitchens and bathrooms with a window open or by using a humidistat extractor
3. Close kitchen and bathroom doors when the rooms are in use
INSULATE YOUR HOME
1. Insulating lofts / cavities can help keep the building warm
We believe that rising dampness exists, however it is not as common as is made out by many damp proofing contractors. Rising damp usually occurs in walls where the foundations extend down below the ground water table. The water rises either through the bricks or the mortar joints due to fine capillaries or pores in the materials. (A process known as 'Capillarity') There are three main factors that affect the quantity of moisture absorbed by the wall and the height to which it rises;
1. The capacity of the wall material to absorb moisture
2. How wet the ground is
3. How quickly the moisture can evaporate
Water will continue to rise up the wall until it meets a physical barrier. The construction of most modern buildings includes a damp proof course (DPC) - a layer of impermeable material (eg: slate, bitumen, plastic) built into the external walls just above ground level. The DPC prevents moisture rising up the wall construction. In the absence of a damp proof course, then water has the potential to continue to rise up the wall to heights of approximately 1.5m. Many situations where rising damp occurs is often due to the bridging of the existing damp proof course rather than the absence of one. Older building, particularly those with solid stone or brick external wall, do not always have a DPC. It is assumed that rising dampness is likely to be a problem in these types of properties, however a full investigation of the cause of dampness must be carried out to determine if rising damp is indeed the cause.
A small leak in a water supply, central heating or internal drainage pipe can cause extensive dampness over a period of time. Signs of dampness though may only appear some distance from the leak.
Spills from water tanks, cisterns and washing machines can cause water to run through cracks and joints. This can spread underneath floor coverings causing further problems.
Water ingress will occur where the building is unable to prevent water entry where water is present, Water can be driven in by wind and rain, attracted by salts and drawn towards the warmth. Penetrating dampness can occur through many building defects, examples include;
RAINWATER GOODS - Blocked valley gutters and downpipes can cause rainwater to 'pond' and overspill. Parapets and chimneys can also get very wet, with water draining downwards to other parts of the building causing internal dampness if not adequately protected.
LEAKING ROOFS - Common defects of roofs include corrosion of nails that fix the tiles to the battens, cracked or missing roof tiles, mortar missing from the ridge tiles. These defects can all allow the passage of moisture into the fabric of the building
RENDERING - Defective render can occur mostly on external walls caused by penetrating rain, evaporation and condensation. These thermal stresses can cause shrinkage and cracking of the render.