The implementation of the interior project development delays so that the total duration of the development a setback, the occurrence of the delay was due to waste in project activities. Based on this, this study aims to analyze the types of waste and their causes and make an improvement that can result in timely scheduling for the next SOHO (Small Office Home Office) project. The approach used is the Project Management and Lean Construction. Project management approach by monitoring the s curve and identify the critical path using the critical path method (CPM), this approach is used to see differences in weekly progress and the critical path in interior work. The lean construction approach uses value stream mapping to identify waste in current state mapping, fishbone diagrams to describe the causes of waste, and future state mapping to describe improvements that will be made in order to produce timely project scheduling. The result of this research, there is waste in the critical work of this project, it is a waste of defects, inventory, and waiting. The cause of waste that occurs in the implementation of interior projects is waste waiting because the material is stored in a warehouse located far from the workshop, so it takes a long time. Waste defects by checking material samples and waste inventory by submission of materials with the same specifications. So from the proposed improvement, the duration of the interior project is 15 days faster from 85 days to 70 days.The implementation of the interior project development delays so that the total duration of the development a setback, the occurrence of the delay was due to waste in project activities. Based on this, this study aims to analyze the types of waste and their causes and make an improvement that can result in timely scheduling for the next SOHO (Small Office Home Office) project. The approach used is the Project Management and Lean Construction. Project management approach by monitoring the s curve and identify the critical path using the critical path method (CPM), this approach is used to see differences in weekly progress and the critical path in interior work. The lean construction approach uses value stream mapping to identify waste in current state mapping, fishbone diagrams to describe the causes of waste, and future state mapping to describe improvements that will be made in order to produce timely project scheduling. The result of this research, there is waste in the critical work of this project, it is a waste of defects, inventory, and waiting. The cause of waste that occurs in the implementation of interior projects is waste waiting because the material is stored in a warehouse located far from the workshop, so it takes a long time. Waste defects by checking material samples and waste inventory by submission of materials with the same specifications. So from the proposed improvement, the duration of the interior project is 15 days faster from 85 days to 70 days.