The Use of Unmanned Aerial Vehicles for Sloped Roof Inspections – Considerations and Constraints

Building roof inspections should be performed periodically to ensure repairs and replacements are done in a timely manner. These inspections get neglected on sloped roofs due to two factors: the inefficiency of manual visual inspections, and the difficulty of accessing sloped roofs. Walking a roof to inspect each tile is time consuming. As roof slope increases so does this difficulty, increasing the time needed for an inspection. Additionally, there is an inherent safety risk involved. Falls from roofs tend to cause serious and expensive injuries. These two factors, safety and efficiency, motivated this study, the purpose of which was to determine whether Unmanned Aerial Vehicles (UAVs) can be used to perform sloped roof inspections efficiently, thus eliminating the safety risk involved in manual inspections. The metric for determining whether this is possible was that there is a UAV available on the market that (1) produces images in sufficient quality to make maintenance decisions, (2) can be flown efficiently enough so that the inspection process can be done in less than two hours for a building with a roof of about 30,000 sqft, (3) can be controlled safely by amateur pilots, and (4) is reasonably priced. The study was done in three phases. Phase 1 addressed the choice of UAV. Phase 2 explored image quality and UAV flying. Phase 3 developed the optimal approach. The study found that an economic UAV can be used in a way that makes manual inspections unnecessary. Still images and manual UAV control were sufficient and large roofs could be done in well under two hours using a three-step approach with images taken at various heights. This study has therefore identified an economical and effective technology-based alternative process for sloped roof inspection using UAVs that eliminates the risk of working at height.