The architectural heritage of many Latin American countries includes buildings constructed with adobe, a fragile material characterized by low tensile strength, limited energy dissipation, and significant seismic vulnerability—particularly in structures with irregular floor plans. Recent earthquakes have underscored these weaknesses, exposing critical deficiencies in their structural performance. This study proposes a streamlined methodology for the seismic assessment of heritage adobe structures through linear finite element analysis (FEM). Using the historic Simón Bolívar School in Quito, Ecuador, as a representative case study, the research examines the influence of geometric irregularities and boundary conditions on stress distribution, displacement patterns, and potential collapse mechanisms. The findings identify critical damage zones that exceed allowable thresholds, emphasizing the need for timely seismic retrofitting. Additionally, the study explores how mesh type and discretization strategies affect the reliability of FEM results. By comparing simplified and detailed modeling approaches, it highlights the importance of calibrating material properties and boundary conditions in relation to structural geometry. Although linear methods cannot capture damage progression or material degradation, they serve as effective preliminary diagnostic tools to support rapid post-earthquake decision-making. Ultimately, this research contributes to the development of efficient evaluation frameworks and practical guidelines for seismic intervention and conservation of adobe heritage buildings in high-seismic regions.