Sandwich structures are widely used in lightweight engineering applications due to their high stiffness-to-weight ratio and structural efficiency. With the advancement of Additive Manufacturing (AM), the integration of complex lattice architectures as cores in sandwich beams has become increasingly viable, enabling the fabrication of highly optimized structures with fewer manufacturing steps and improved performance [1]. This study conducts a comprehensive analytical and numerical investigation on sandwich beams featuring AM lattice cores and composite facesheets. The analytical framework is built upon the Refined Zigzag Theory (RZT), which enables accurate layerwise modeling and superior prediction of displacement and stress fields, particularly in the transverse shear and interlaminar domains [2]. Finite Element Method (FEM) simulations using ABAQUS are performed under both simply supported and cantilever boundary conditions to validate the analytical outcomes. Results reveal that the zigzag model offers excellent agreement with FEM predictions, outperforming classical shear deformation theories in terms of through-thickness stress continuity and displacement accuracy. These findings emphasize the strength of advanced zigzag-based formulations in assessing and optimizing the structural behavior of AM-enabled sandwich composites.