Purpose - Generally, the implementation of lean manufacturing (LM) starts with the development of value stream maps. However, it has been found that value stream mapping (VSM) suffers from various shortcomings. Hence, researchers have suggested the use of simulation along with VSM. The purpose of this paper is to present an application of VSM with simulation during the design of lean manufacturing systems (LMS) using a case study of an organisation following a job shop production system to manufacture doors and windows. Design/methodology/approach - Simulation models were developed using QUeuing Event Simulation Tool for the case organisation to demonstrate how the case organisation will be changed after implementing various LM elements, apart from analysing the impact of implementing these LM elements on the organisation's performance. Findings - Simulation studies were carried out for different scenarios such as "beforeLM" (current state VSM) and "after LM" (future state VSM). It was found that the case organisation can achieve significant improvement in performance and can meet the increasing demand without any additional resources. Practical implications - It is believed that this paper will enable practitioners to appreciate the role of simulation in helping them understand how the operations department of the case organisation will be transformed during the design of LMS. Originality/value - According to the authors' knowledge, no case study exists in the literature that discusses the application ofVSMwith simulation in an organisation thatmanufactures doors and windows using a job shop production system. Furthermore, the paper simulates the impact of those LM elements which were not considered by other researchers on the performance measure of the case organisation. © Emerald Group Publishing Limited.