<p>As China intensifies its efforts to renovate older residential areas, the renewal of housing built between 1980 and 2000 has reached a critical juncture, necessitating a shift from broad-brush approaches to more refined, precision-oriented renovation strategies. However, standardized diagnostic evaluation criteria and decision-making frameworks for pre-renovation assessment remain underdeveloped. This study builds upon existing research in building regeneration, constructing a diagnostic evaluation process for existing residential buildings from an architectural perspective. The process comprises three phases: data collection and integration, visual model construction, and diagnostic evaluation and analysis. Focusing on key residential components—roofs, walls, exterior windows, and shading elements—the research integrates Building Information Modeling (BIM) technology to propose a diagnostic grading system based on renovation intensity. It employs a comprehensive assessment method combining qualitative diagnostics with quantitative indicator analysis, culminating in the development of a diagnostic evaluation template. The methodology is then applied to two typical residential buildings in Shenzhen, encompassing the collection, integration, and diagnosis of key element information, followed by further evaluation based on diagnostic conclusions to guide renovation design. This research provides scientific guidance and decision-making direction for the refined renewal of existing housing and the formulation of related standards and guidelines, enhancing decision-making efficiency with advanced demonstrative effects and forward-looking insights.</p>