ABSTRACT
Wood is probably the oldest constructional and decorative material known to humans and is still widely used in buildings today (Cartwright and Findlay, 1968). Timber used in construction, either for decorative or structural purposes, is in biological terms dead wood. In nature wood on the forest floor would become wet, surrounded by organic material and colonized by decay organisms. The process of microbial colonization and decay of wood is a dynamic one in which the nature of the prevailing microenvironmental conditions is continually modified by the process of decay itself. Microorganisms such as mould, fungi, bacteria and insects degrade wood by their complex enzymatic digestive systems, eventually converting the wood to forest floor litter. This ecological succession is part of a natural cycle (Hickin, 1963, 1975; Levy, 1982). Many of these microorganisms are found both in the forest and in buildings. Serpula lacrymans (dry rot) is not known to live outdoors in the United Kingdom but is found wild only in the Himalayas. The common factor in this decay process is moisture. Buildings can provide specialized ecological niches and ideal microclimates for growth and proliferation of timber decay organisms, especially if they have been suffering from chronic water penetration, poor ventilation and gross neglect (Hutton, 1990a).
