Roofing is one of the building components which is most subject to deterioration. Maintenance and renewal of roofs are, therefore, crucial and require frequent inspection and good understanding of roof deterioration with time. In an effort towards facilitating roof condition assessment and subsequent repair decisions, this article first discusses the previous studies related to roof inspection and deterioration, followed by a two-stage survey among roofing experts. The first stage elicits the most common defects, their contribution to failure, symptoms of poor and critical roofs, and impact of roof deterioration on other components. Fourteen survey responses were obtained from the Toronto District School Board related to school buildings with low-slope built-up roofs. Based on the first-stage results, a pictorial database of roof pictures with different defects was created and initially ranked. The ranking of pictures was then confirmed through the second phase of the survey. The research provides a better understanding of roof deterioration and the developed pictorial database acts as a visual guidance system to facilitate fast and less subjective inspection of roofs, and ultimately to better asset management of building facilities.