Mould and Damp
Mould forms on surfaces where moisture condenses. The relative humidity of the room and the surface temperatures work together. Once the termperature inside a building has the heating turned off the temperature will drop and the air cannot carry the same amount of moisture. If that air then hits a colder surface condensation will occur.
A condensation risk analysis of the surface can assist in identifying areas of concern.
Additionally, destructive testing may be required to assess moisture contained inside the element. Identifying the source of the excess moisture and removing it is the key.
Building materials such as Cob or Marl need a certain level of moisture to maintain the cohesion between the particles of clay. Rendering it in sand and cement render will keep too much moisture in.
Similarly, certain types of insulation seals moisture into a structure.
Assessing the causes of mould and damp should generate a comprehensive report on the building as a functioning structure.
Timber framed buildings require particular care. When party wall works are carried out on timber framed buildings proposed works should take into account vapour and moisture.
Thermal imaging reveals concealed defects.
Relative humidity (RH) is a key measure. This a plot of RH taken during a damp analysis to assess the potential for mould growth.
Ventilation.... In this property the fans had been incorrectly installed and were transferring the humid air around the flat instead of venting it to the outside.
Sources of moisture need to be considered. In this image incorrect sand and cement was used decades ago to seal the marl. Moisture wicked up into the walls of the building for approximately 35 years and the walls could not breath. This resulted in mould growth on the inside, as a result of this the whole first floor floor plate timbers rotted away.
Mould growth inside the wardrobes caused by incorrect airbrick placement behind the back panel. This cooled the surfaces down and caused moisture to condense at a lower temperature inside the wardrobe
Sources of moisture are sometimes obvious. This roof has a history of roofers repairing elements incorrectly. The walls become saturated and this moisture will seek an evaporation route.
