Article By Russel Rafton https://www.dryfix.net/
Contrary to the belief mould is not always a symptom of condensation, and it’s not unusual to find mould growth where there has been no condensation at all, as in these images. This is because moulds don’t actually require physical water for germination, moulds only require the presence of moisture which can also be supplied in the form of water vapour. The optimal water and temperature requirements for moulds differ from species – species and moulds can be categorised by their requirements to water. We generally refer to this as Water Activity (AW) which is a basically a fancy term for Relative Humidity (RH). Xerophilic moulds such as, Aspergillus Flavus can grow and reproduce in conditions with a low water activity as little as 80% RH, whilst hydrophilic moulds such as, Stachybotrys require a much damper environment with conditions above 90% RH or AW.
Mould Germination
But why does mould always seem to germinate in corners?….Well, mainly due to temperature and air movement as well as a host of other factors. The corner of rooms particularly external are often the coldest. This is because of how air circulates a room. As heated air currents move around they sweep the corners leaving the corners slightly cooler and the air within them still. The lack of air movement in corners means spores are not disturbed and there’s often an abundance of food sources present due to build-up of dirt and organic matter.
As can be seen on the attached thermal images, the external corners of this room are noticeably cooler than the rest of the walls, by about 3 degrees C. This means the air within the corners is a little damper than the air within the centre of the room or against the other walls. We refer to this air as the boundary layer, the layer of air adjacent the walls surface. The conditions within the boundary layer can be considerably different due to cooling caused by the walls lower temperature which together with the lack of air movement can create the ideal habitat for the germination of mould spores. That is why you’ll often notice moulds in the corners of rooms first.
As can be seen on the attached thermal images, the external corners of this room are noticeably cooler than the rest of the walls, by about 3 degrees C. This means the air within the corners is a little damper than the air within the centre of the room or against the other walls. We refer to this air as the boundary layer, the layer of air adjacent the walls surface. The conditions within the boundary layer can be considerably different due to cooling caused by the walls lower temperature which together with the lack of air movement can create the ideal habitat for the germination of mould spores. That is why you’ll often notice moulds in the corners of rooms first.
