The meeting of milestones presents a constant challenge in construction projects. One root cause behind this challenge is the presence of variability in the project workflow. In fact, impacts of variability at both trade contractor level and project level remain difficult to manage. This paper aims to analyze impacts of variability in the workflow caused by rework and fluctuating work quantities.Towards this end, production data of two residential construction projects were collected and a mixed method of mathematical and simulation modeling was used in order to analyze performance and productivity at both trade and project levels. Performance metrics such as completion times, work-inprocess levels and delays were then measured in different real-life production scenarios. The findings clearly show that the workflow variability significantly downgrades performance metrics by inflated completion times, longer queues of uncompleted jobs and excessive delays, resulting in the productivity loss. This work contributed to the body of knowledge in engineering management by enhancing the insight into workflow variability and its impacts on tangible performance measures.The results clearly show that productivity and performance in the construction production can be improved by stabilizing the workflow in the interconnected network of trade contractors.