Identification, Classification and Ranking of the Causes of Building Collapse in Lagos, Nigeria from 2012 to 2024

The incidence of building collapse in Nigeria has continued unabated, leading to the loss of lives, injuries, loss of properties, investments, and future commissions. This frequency of occurrence plummets in cities with a propensity for vertical developments and several causes ranging from the use of substandard construction materials and illegal conversion of buildings to failure of key structural elements. This work examined the incidences of reported building collapses in Lagos, Nigeria, from 2012 to 2024 and the attendant increasing loss of lives, properties, and injuries, with a view to determining leading causes of building collapses, its classification, and ranking. It also highlights the casualties arising from these occurrences. There has been conflicting information on casualties and damages resulting from building collapses in Nigeria, perhaps due to ineffective coordination amongst agencies responsible. This has undoubtedly led to increased research interest in the subject matter of building collapse in Nigeria. Findings of this study revealed the leading causes of building collapse in Lagos in decreasing order to include primary failure of key Violation of building regulations/approvals, distressed buildings marked for demolition, torrential rainfall/rainstorm/thunderstorm & secondary failure, structural failure including underreinforcement/ improper anchorage of reinforcement and structural defects, and illegal conversion of buildings/addition of suspended floors/illegal renovation. A total of 106 cases of building collapses were identified to have occurred in Lagos within the period under consideration with average frequency of occurrence of 49.89%, leading to the confirmed death of at least 357 persons from 2012 to 2024 alone. It was comparatively established that the leading causes of building collapse in Nigeria vary from one place to the other. Recommendations were made in line with the evaluated leading causes of building collapse in Lagos in accordance with the stages of building and structure of the National Building Code.