Congestion is one of the common occurrences in most building construction projects executed within the business districts of a city. Owing to this, construction doers have been forced to manage resources in a confined area, leading to frequent workspace conflicts. Besides, construction firms tend not to be innovative in organizing sites. In this regard, this study initiated to investigate the practice of site organization in congested building construction sites located in the business districts of Bahir Dar city. Quantitative and qualitative data were gathered to address the constructs of the study. The study used mixed methodological approaches that consisted of questionnaire surveys and case study analysis. The sampling method adopted was a purposive sampling technique. Survey questionnaires were then administered to 73 professionals involved in active non-residential building construction projects. Four case studies involving interviews and structured observations were also investigated to validate the quantitative findings. The quantitative data obtained from a survey questionnaire were then analyzed by employing the Mean score (MS) formula using SPSS V 26. While data collected through interviews and structured observations were qualitatively analyzed. The results of the study indicated that inadequate amount of space (MS=4.34), location of the site(MS=4.27), limited access to the site and/or material stacked on the access(MS=4.18), and poor site organization(MS=4.12) are major causes of congestion that have been generating problems such as difficulties in materials storage(MS=4.26), impose manual handling of material (MS=4.21), difficulty in delivering materials(MS=4.19), and productivity loss(MS=4.14) in building construction sites situated in restricted urban settings of Bahir Dar city. Further, the study has also identified that most of the construction projects have no site organization plan. As a result, a site organization framework that enables the re-organization of the site as the schedule evolves was proposed to improve the site organization practice of spatially restricted sites. Its applicability was then demonstrated on actual case study projects using Sketchup pro-2021 and MS project 2019. The study's general findings and proposed methodology can be used to improve present site organization practices. Finally, the study suggested that as part of preparation and budgeting proper site organization shall be done by contracting parties.