Environmental factors affecting biodeterioration
Understanding ecology
When considering any form of biodeterioration, there are 3 factors of concern:
- the material;
- the environment; and
- the organism.
Ecology as an aspect of science is usually confined to a very close analysis of the interaction of organisms with one another and with their environment. The environment in which any organism lives contributes physical, chemical and biological factors that have a bearing on the settlement, growth and development of an organism.
The environmental factors affecting the decay of timber are temperature, water, humidity and ventilation. Fungi differ in their optimum temperature requirements, but for most the range is approx. 20-30ºC. The optimum temperature for dry rot growth in buildings is about 23ºC; maximum temperatures are about 25ºC and the fungus is rapidly killed above 40ºC. Timber moisture contents of 20-30% in buildings are ideal for dry rot attack and other infestations.
The environmental and non-environmental parameters considered most hazardous to building fabric, buildings' environments, structures and contents are:
- relative humidity;
- ultraviolet light;
- air temperature;
- dust;
- pollution;
- pests;
- handling;
- visitors;
- fire and water;
- air movement; and
- cultural, organisational and management factors.
Moisture in buildings
The factors that contribute to the moisture supply in buildings include:
- penetrating and rising damp;
- condensation;
- building disaster;
- construction moisture; and
- building defects.