This thesis is about finding, identifying, and then using, changes in nails as a forensic method to date buildings, extensions to buildings, repairs, and later insertions.0The thesis traces the historical development of European/Western nails, isolating the three main world nail industries and their export markets. It then provides case studies for British and Australian nails. Using a process of synthesis, it builds sets of dating charts by decade, of direct use to researchers in the field and to all those interested in dating aspects of heritage buildings.00The thesis makes a series of conclusions, primary of which are: 0- The morphologies of Western nails emanate from Roman enforced practices;0- The Liège nail industry was the first and foremost world player;0- Developments of an English nail industry sprung from invention and from transport solutions;0- The American cut nail industry was enabled by their early switch to softwood framing in the building industry, and by massive, sustained, population growth;0- The system of dating developed by the thesis was found to work best for decades starting in 1830, but it loses accuracy after 1890.0Recommendations are made for future studies based around information found during the research.