Performance of Construction Workers in High-rise Building Projects in Nairobi: Quantitative and Qualitative Aspects

The construction industry in Kenya is a vital driver of economic growth, yet labour productivity continues to lag behind global benchmarks. This study investigates the performance of construction workers in high‑rise building projects in Nairobi, focusing on both quantitative and qualitative dimensions of labour performance. Guided by human capital theory, the research conceptualizes worker performance as a dual construct comprising labour efficiency and labour effectiveness. A quantitative survey design was adopted, targeting 125 registered high-rise projects, with data collected from accredited site supervisors. The operational framework measured efficiency across seven core work categories, namely, site preparation, scaffolding, concreting, walling, plastering, tiling, and building services, while effectiveness was assessed through quality of work and training, skillset, and development indicators. Reliability and validity tests confirmed strong internal consistency (Cronbach α > 0.95) and construct validity. Results revealed an overall labour efficiency of 66.8%, with concreting recording the highest efficiency (68.0%) and building services the lowest (65.4%). Effectiveness measures highlighted significant associations between training, skillset development, and quality outcomes. The findings underscore the need for systemic reforms in training, mechanization, and sociotechnical integration to enhance productivity. Policy implications include establishing standardized labour benchmarks, incentivizing technology adoption, and mandating continuous professional development. Practically, firms should embed lean construction practices and quality assurance systems, while future research should integrate mixed methods to capture worker perspectives. This study contributes to evidence-based strategies for improving labour performance and competitiveness in Kenya’s construction sector.