The side setback areas of buildings are generally underutilized urban spaces. Often, they are used as unauthorized commercial spaces, which lead to legal struggles and safety and sanitation hazards. However, the presence of these establishments implies a demand for using these spaces, and many argue that such structures enhance and vitalize cities. This study establishes a new direction for utilizing side setback areas that harmoniously meets the demands of city dwellers and business owners while ensuring safety and compliance with regulations. We examined the utilization status of 371 side setback areas in various districts of Seoul and surveyed 20 urban management experts. Th results indicate that at least 30% of all buildings in the study repeatedly violated laws regarding the use of their side setback spaces, and 100% of the experts agreed that the current regulatory system is inflexible. Our analysis suggests that reform is needed and offers tangible guidelines so that these generally underutilized spaces may become useful when safety and sanitation requirements are met. In the context of overpopulated urban spaces, side setback areas can be repurposed to meet the needs of urban residents while ensuring safety and sanitation.