The purpose of any building is to serve its occupants: support their well being and meet their needs- living, working, recreation etc. However, when building materials deteriorate they do not only fail but also undermine the ability of buildings in meeting their functions. This book identifies and evaluates microorganisms that deteriorate timbers in buildings under Nigerian microclimates in light of sustainability indicators. The techniques of culturing, and biochemical tests were used on 850 of 10 grammes collected in Sudan savanna, Guinea savanna, Rain forest, and Swampy rain forest regions. Contaminations by bacteria and fungi were analysed based on microclimates surrounding buildings. Timber species that were susceptible to microbial deteriorations were identified. The areas with high prevalence of biodeteriogens suggest threat to sustainability and it is recommended that such susceptible timber species be used in regions that are safer. This book is useful to the Maintenance, Facility and Estate managers, Occupant and Owner, Employer, Health and Safety officer, Surveyors, Builder, Architect and Engineers in the construction fields.