Evaluation of Lump-Sum Contract Performance on Public Buildings in Niger State

Lump-sum contracts are among the most frequently used procurement options in Nigerian public sector construction, yet their performance in delivering projects within budget and on schedule remains inconsistent. This study evaluates the performance of lump-sum contracts in the delivery of public buildings in Niger State, focusing on projects undertaken by the Ministry of Infrastructure between 2020 and 2024. A descriptive quantitative design was used, with 75 respondents comprising quantity surveyors, contractors, and government project officers completing structured questionnaires. Project cost and time performance data were collected from 30 completed projects. Data were analysed using descriptive statistics and deviation analysis. Findings show that 63% of lump-sum contracts reviewed experienced cost growth, with an average cost overrun of 19.4% attributed primarily to design changes, inadequate drawings at tender stage, and provisional sum adjustments. Programme overruns averaging 28% of planned duration were also recorded. The study identifies poorly defined scope at tender, absence of detailed contract drawings, and weak contract administration as systemic weaknesses in lump-sum procurement in Niger State. Recommendations include mandatory completeness checks on tender documents, the appointment of resident quantity surveyors on all projects exceeding a defined value threshold, and post-project reviews to capture lessons learned. This research enriches the procurement performance literature in North Central Nigeria. Keywords: lump-sum contract, public buildings, Niger State, cost performance, contract administration