The regulation of psychological privacy and the realization of privacy quality in residential architecture are fundamentally intertwined with the structure and tangible nature of physical boundaries, as the quality of spatial demarcation directly influences the control of environmental stimuli and the segregation of public and private domains. However, in the physical transformations of contemporary housing, the excessive dominance of transparency or the irregular arrangement of boundaries has challenged the monitoring of visual and acoustic information, thereby altering traditional patterns of privacy. The primary objective of this study is to provide a comparative analysis of the role of spatial boundary-making mechanisms and degrees of physical solidity on the level and quality of privacy preservation within highly replicated typologies of residential buildings in District 1 of Tehran. This study is qualitative in nature, employing a descriptive-analytical method grounded in logical reasoning. Initially, the indicators for measuring enclosure and privacy regulation were extracted through literature reviews, and subsequently, the research variables were analyzed individually and comparatively across selected spatial cells of the case studies in this district. The results indicate a direct and hierarchical relationship between the solidity coefficient of boundaries and the degree of privacy attainment in spaces. Consequently, deep spaces such as the master bedroom, by relying on solid boundaries, achieved the highest privacy index, while public and common areas such as the parking lot remained at the lowest level. Furthermore, the findings reveal that in addition to the degree of solidity, the geometric configuration of boundaries plays a vital role in mitigating stimuli. If the placement of blurred boundaries or openings lacks a specific order and rule, the space suffers from visual and acoustic crowding, leading to a drop in the privacy index. Conversely, increasing the spatial area in conjunction with reducing the width of thresholds enhances the physical enclosure coefficient. Moreover, utilizing modern semi-solid elements at thresholds considerably elevates privacy stability and quality without inducing spatial contraction.