The need to develop a highly accurate set of “as-found” condition documents presents a significant challenge in the practice of architecture for any project involving an existing building. For the majority of new buildings, an adequate construction documentation package can be developed simply by applying industry standards along with carefully engineered and well-detailed methods and materials. In contrast, projects involving intervention in existing buildings require an in-depth understanding of the existing building, its methods of construction, and any deterioration that exists. This requirement is particularly critical in the practice of preservation architecture, when renovation, adaptive re-use, and/or restoration projects affect structures with physical fabric of intrinsic historic value. Existing guidelines, such as those of HABS, attempt to ensure that recording is performed in a useful manner that meets certain minimum standards; however, these address only visible conditions, those that can be measured and photographed and those where physical reality is fully observable. Advancements in technology have allowed a marked increase in the ability to understand both the layout of concealed elements, such as wood framing configurations, and the existence of deterioration mechanisms invisible to the naked eye. Unfortunately, these advancements have not necessarily corresponded with the development of standards and guidelines for systematically conducting this type of investigation. Based in part on the author’s experience as a preservation architect, this thesis outlines a methodology and approach for documenting concealed fabric and conditions in historic buildings.