Flow is a key concept in Lean Production and is particularly important in construction. Due to the complexity of projects, in part due to managerial practices adopted, much variability exists in construction resource flows. Production system design can be used to eliminate at least some unwanted variability and then reduce the impact of remaining variability by using buffers in order to improve such flows. Accordingly, planners may add buffers of certain sizes in certain locations into the system, or use more systematic, adaptive, data-driven methods. With this in mind, the authors initiated a systematic literature review (SLR) on buffers in construction. The paper contributes to knowledge by defining the term 'buffer' and providing a characterization of buffer types and methods of deployment. Despite advances in understanding and method development, no one method stands out. The methods as described fall short of being able to both proactively determine buffer sizes and locations in the production system to suitably accommodate anticipated needs, and also reactively adjust them in light of system design changes. The use of SLR as the research methodology has well-known limitations, but the findings were revealing, and follow-on research will cast a wider net for relevant literature.