This paper attempts to characterize workflow in construction and thereby to provide a measure for flow at various levels of the construction process. A process based approach is adapted to model flows in construction. Construction of a multi storied residential building super-structure involving identical activities for each floor cycle was selected to observe, document and analyze the characteristics of construction activity flow. The detailed functions and relationships between resources, materials and information for each floor cycle was documented and analyzed for flow characteristics. Queuing theory approach is used for analysis and parameters for quantifying the flow characteristics are proposed. A preliminary model for characterizing flow is formulated. The application of the model for analyzing flow states is discussed.