PurposeLean construction is a technique that aims at reducing waste in construction and maximizing productivity. The purpose of this paper is to discuss the effectiveness of Lean technique in managing construction projects.Design/methodology/approachA case study of structural steel erection project was chosen where the value stream mapping lean tool is applied and the possible improvement in productivity was observed. The current state of the activities in the erection process was mapped first which was followed by preparing the Future State Map of the activities after eliminating the non-value adding tasks.FindingsThe modifications from Future State Map were carried out at the project and the results exhibited a substantial increase in productivity by reducing the project duration by 13 days which is about 30 per cent savings from the expected completion time after the implementation of Lean technique.Originality/valueTraditionally lean concept has been widely used in process-oriented manufacturing industry whereas it is relatively new to the project-oriented construction industry. This current research has focused on applying lean tool to a real time construction project at the site level and measuring its outcome practically. The results of this study are real and affirm the effectiveness of applying lean concept to construction projects. It will be major paradigm shift in terms of managing construction projects.