Ho Chi Minh City's urban morphology, shaped by its colonial architectural heritage, facilitates the integration of street vendors and their temporary structures within public spaces. This study examines the spatial relationship between colonial-era school buildings and temporary vendor structures on adjacent sidewalks, exploring how architectural features influence their placement, orientation, and design. By mapping colonial-era school sites in central district, the research identifies how setbacks, façade articulation, and stationery adjacent to the street contribute to urban landscape that accommodate temporary structures. The study classifies 4 distinct typologies of modular vendor structures, analyzing their architectural components, mobility systems, and spatial requirements, and reveals how these ephemeral elements adapt to the physical constraints of the built environment. Recent regulatory measures requiring fees for sidewalk usage disrupt this spatial equilibrium, challenging the symbiotic relationship between permanent and temporary structures. The finding contributes to adaptive reuse discourse, proposing strategies for formalizing the integration of temporary structures while preserving the colonial urban fabric. It suggests design interventions that balance architectural heritage conservation, and the potential transformation of temporary structures, offering insights for architects and urban planners working with similar historical landscapes.