To discover more about the damp problems that our surveyors find themselves up against, we recently shadowed our London damp proofing specialists whilst they carried out a damp inspection to see first hand how a survey is carried out and how a diagnosis of the damp problem is reached.
The property in question was a ground floor flat within a large detached brick built property constructed in circa 1990s. Upon carrying out the inspection it was evident that the property had been suffering from not one but three different types of damp: penetrating damp, rising damp and condensation.
During the external inspection of the property it was clear that the left hand flank wall was earth retaining up to a height of about 400mm as the drive for the garage sloped up towards the rear of the property. In addition there were also defects in the shape of cracked render plinths, render plinths in contact with the ground as well as downpipe and gulley fractures.
As a result the reverse side of the wall suffered from penetrating and rising damp, leaving a clear tell tale sign of a damp tide line. By carrying out a dampness reading of the inside of the wall, using a protimeter it was found that the wall contained high readings of moisture content within the wall as well as evidence of salt contamination. 
Black spot mould growth was also found on various plaster walls in addition there were also signs of surface moisture condensation on the glass and window frames. An air extraction unit was installed within the bathroom and was operated by a pull cord. However, the fan appeared to be underpowered and was therefore not functioning properly. This, coupled with a lack of ventilation unit in the kitchen indicated an internal condensation problem within the property.
To check further for condensation issues within the property measurement of the moisture content within the wall were taken. The internal moisture levels were recorded at 57-59% RH ( Relative Humidity), which is considered to be normal however the mould growth suggested that during the colder months the relative humidity was much higher.
Condensation occurs when the water content of air rises above a level referred to as the dew-point. When the relative humidity reaches a figure of approx. 60%, water droplets will start to form on the cooler surfaces such as windows and walls whether they are insulated or not. Relative humidity is described as the amount of moisture in the air expressed as a percentage. Once the relative humidity reaches or exceeds 60% moisture content the atmospheric conditions for condensation to occur become ideal.
Moist air is created by many factors such as the lack of adequate ventilation. Up to approx. 17 litres of moisture can be produced daily in some homes.
Warm air is capable of carrying a larger amount of moisture than cool air. When the air is carrying all the moisture it is capable of at that temperature, it is said to be at saturation point. The temperature when this occurs is called the dew point. If this air meets a surface which is at a lower temperature than the air temperature, the moisture in the air will condense into water upon the cooler surface thus forming condensation.
The most obvious symptoms of condensation are surface moisture and mould growth. The mould growth occurs initially as spots increasing to larger patches. Four of the most common moulds known in residential properties are Penicillium, Trichoderama, Aspergillus and Pullularia. Mould usually appears as unsightly growths in various colours including green, yellow, pink, black, grey or white.
Moulds require very little nutrients, but moisture is essential for their propagation and they tend to occur as a result of condensation. Materials such as wallpaper, clothes, shoes and other fabrics may also be affected.
In conclusion, condensation is indeed a complex subject of atmospheric moisture and air movement. The cause and solutions are dependent upon many factors for example: Construction type, insulation within the property, room shapes and sizes, quantities, size and location of furnishings, the number of habitants and their habits just to name a few.
Damp issues are often misdiagnosed and it can be difficult to determine if a property is suffering from condensation, penetrating, rising damp or all three within the building. To ensure correct diagnosis a survey from a damp specialist is recommended. Timberwise have been treating properties with rising damp for over 45 years and are specialists in identifying and applying rising damp treatments.
If you suspect you have rising damp don’t panic! Call our rising damp specialists on 0800 288 8660 or complete our on-line damp survey request form to arrange a surveyor to visit.
