PROTECTION & REMEDIAL TREATMENT 4.1 139 CATHEDRAL COMMUNICATIONS THE BUILDING CONSERVATION DIRECTORY 2025 circumstances and location that you would normally find it. It is therefore difficult! Generally mould requires a level of moisture to sustain itself with the help of food such as dust and dirt. It can affect the substrate on which it is growing and if left it will continue to colonise. During any investigation one must realise that it is the building and its use that creates the environment in which mould can flourish. The eradication of mould therefore involves its removal and eradicating the reasons why it grew in the first place. ENVIRONMENTAL INVESTIGATION AND ASSESSMENT The process should commence with a desktop inspection which will then enable a much more effective and economic investigation of the building as outlined in the flow chart opposite. As with all stages of the process, it relies upon the person undertaking the inspection to have an excellent understanding of the subject in all respects. This means knowing the age of the building, its construction type and the materials it’s constructed of, understanding exactly what damp is and where condensation occurs, and being familiar with the different types of mould and what the possible causes of all these problems are. It also means knowing what influences the changes in the way buildings have been constructed over time, including changes in legal requirements and building regulations. One other essential element to be covered in the desktop analysis is the location of the building in terms of the weather exposure zone, alongside the geography around the building. Issues considered here will include exposure to heavy wind-driven rain, whether the building is sheltered or not, it’s vicinity to other sources of water such as streams, ponds and the sea, the location of any nearby trees, and the like. It would also be useful at this stage to understand the history of work that has been undertaken to the building, and this doesn’t just include alterations but also repairs that may have been carried out, complaints of disrepair and information about whether any previous repairs have succeeded or not. Once the desktop inspection has been undertaken, then the site inspection can begin. This should include discussions with the occupants of the building to find out as much as possible about any observations they have, any issues concerning the way the building is used and any information they can provide that will help you to work out how much moisture is being produced through the use of the building. This means understanding the number of occupants, the heating patterns and the way the building is ventilated amongst many other issues. The inspection itself will commence on the outside by looking at the location of the building and what is surrounding it, in order to understand whether it is sheltered or exposed. Next, an inspection of the building’s envelope will note areas of weakness and changes that have taken place, ranging from major interventions such as extensions and external wall insulation, to relatively minor repairs that might have introduced cement mortar repointing, for example. All such changes can influence moisture performance. The external inspection will also mean the use of a hygrometer to record information such as temperature, relative humidity (RH), absolute humidity, vapour pressure and dew point temperature. This is most important as the same type of data will be recorded internally. With external environment conditions influencing internal ones, this is all essential as it also allows the data from the outside and the inside to be compared with each other during any analysis. The inspection of the interior may start at the top of the building and involve exploring each interior space in turn. Observations made will take due consideration of what has been noted on the outside, the information obtained from the occupants of the building and considerations made on the use of the building. Within each internal space observations will be made in respect of damp, mould and condensation. These will be backed up by detailed analysis as necessary, including the use of hygrometers (for measuring RH etc as above), electric resistance meters for measuring damp in timber and electric capacitance meters for walls and solid floors. Resistance and capacitance meters must be used with caution as the readings for timber could be influenced by chemical treatment and the capacitance meter doesn’t provide a moisture percentage. Only radio frequencies provide some indication of moisture present. In order to gauge the moisture present in masonry, plaster and the like, a carbide meter or the gravimetric test method should be used as appropriate. This will all be supported where cavity walls are concerned by the inspection within cavities using borescopes. Dry rot fungal growth. This will only occur in a building with problems, bringing about levels of moisture which are unsatisfactory; a combination of causes including poor internal environment and external condition. An investigation may reveal conditions for dry rot and other types of mould before they actually occur.
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