A taxonomy of urban façade defects and their distribution on façade components: A data-driven analysis of historical inspection reports

Well-maintained building façades are essential for public safety. Major cities across the globe have inspection programs to ensure façade safety. However, accidents caused by falling debris and complaints continuously happen and indicate a need to improve the current inspection practices. A systematic guideline is lacking to achieve comprehensive safety inspections of buildings. A challenge that exists on the path toward a systematic and comprehensive façade inspection process is the lack of availability of common and comprehensive vocabularies for the façade safety inspection domain that extends beyond material-based defects. This research defines a taxonomy of façade defects and relationships of these defects to façade component hierarchies, through natural language processing and machine learning methods employed on more than 2,500 façade inspection reports for three major façade types. Contributions of this work include the taxonomy of defect types and their applicability to façade components, forming the missing but foundational piece for enabling comprehensive inspection of building façades. The study can directly be used in practice to establish a standard inspection practice across various inspection companies and related city agencies.