Construction and Demolition Waste in Lagos State, Nigeria: Waste Material Composition and Challenges to Sustainable Management

Nigeria's construction industry is a driving force of the nation's economy, fueled by the demands of a population exceeding 200 million. Yet, beneath this growth lies a mounting challenge: the generation of vast quantities of construction and demolition waste (C&DW), which remains critically underdeveloped—particularly in urban epicenters like Lagos State. The composition and scale of this waste are shaped by demographic pressures, planning frameworks, construction technologies, demolition practices, and contractors' variable capacities to manage their waste streams. This study investigates the material makeup of C&DW generated at active construction sites in Lagos and systematically identifies the key barriers hindering the adoption of sustainable waste management practices. Employing a qualitative research design, primary data were collected through semi-structured interviews using snowball sampling, with 10 sessions successfully conducted with project managers overseeing multi-million-naira residential and commercial projects across the state. Descriptive statistical analysis reveals that wood or timber dominates the waste stream, accounting for 34.12% of total volume (Mean = 29.70%, SD = 31.50), followed by mortar (13.21%; Mean = 11.50%, SD = 23.10), concrete (9.42%; Mean = 8.20%, SD = 15.10), reinforcement offcuts (8.85%), and rubble (8.62%). Together, these five materials constitute nearly three-quarters (74.22%) of the estimated C&DW volume. A Spearman rank correlation (ρ = 0.855) between material reporting frequency and proportional contribution confirms a strong positive relationship between how widely a material is generated and its volumetric significance. The study further identifies nine barriers to sustainable C&DW management, with the most prevalent being poor worker attitudes (40% of sites), high implementation costs (20%), institutional inefficiency of the Lagos Waste Management Authority (LAWMA) (20%), and logistical evacuation challenges (20%). These barriers were found to exert measurable adverse effects on project safety, quality, schedule, and cost performance. The study concludes that achieving sustainable C&DW management in Lagos State will require a concerted effort—targeted policy reform, capacity-building among practitioners, and the integration of waste planning at the pre-construction stage. Without such measures, the industry's growth will remain tethered to an unsustainable trajectory, with far-reaching consequences for the environment, public health, and economic development.