The aim of the study was to characterise the environment in the Sydney region in respect of atmospheric corrosivity, timber decay risk factors and the corrosion of nails in timber in covered conditions. The study reviewed contemporary research in this field, particularly in Australia, developing an understanding of the durability failure mechanisms for timber and nails in timber. The study looked at the effects of climatic aspects, pollutants, corrosion on timber decay risk factors. The study found that the levels of risk in terms of timber degradation, corrosion and nail corrosion were greatest adjacent to the coast and at marine sites. / Doctor of Philosophy (PhD)