The reduction of slum dwellers through enhanced provision of adequate, safe and affordable housing is one of the critical targets of the sustainable development agenda of the United Nations. By implication, the construction cost of residential buildings needs to be reduced to make them more affordable. Reduction in the cost of cost-significant building elements will lead to substantial reduction in the construction cost of any residential building executed. This paper reports the findings on the cost-significant elements of residential building projects executed in Nigeria with a view to using them to reduce building cost. Cost data on 34 residential building projects executed in various locations of Nigeria between 2008 and 2016 were collected from Quantity Surveying consulting firms in Lagos State, Nigeria using random sampling technique. The cost data were converted to the same base year values using cost indices and then analysed using the Pareto Analysis procedure to obtain cost-significant elements. Findings from the study indicated that the cost-significant elements of residential building projects executed in the study area were electrical services installations which account for 16% of total construction cost, mechanical services installations (15%) and windows and upper floors (10%), respectively. The paper concluded that these cost-significant elements, representing 33% of total number of elements account for 50% of total construction cost. Reduction in the cost of these few elements will lead to significant reduction in the cost of residential building projects executed in the study area.
Key Words: Building, Cost-significant, Elements, Pareto Principle, Projects