In the context of increasing use of geosourced materials such as hemp-clay to address the challenges of sustainable construction, accurately assessing their hygrothermal performance is essential. Hemp-clay walls, which combine insulating properties with natural humidity regulation, are often paired with interior and exterior plasters that significantly influence their overall behavior. A previous study conducted at the LGCGM laboratory using the WUFI software analyzed the hygrothermal performance of such systems under the assumption of a perfect contact between the plaster layers and the hemp-clay layer. However, this simplifying hypothesis does not always reflect the reality of material interfaces. In this study, we propose an advanced modeling approach using ANSYS software, which considers an imperfect contact between the plaster and hemp-clay layers, incorporating interface resistances and discontinuities. Thermal simulations were performed on walls comprising interior and exterior plasters, with material properties (thermal conductivity, density, heat capacity) calibrated through experimental measurements. The results reveal significant differences between the two approaches: WUFI underestimates temperature gradients at the interfaces, while ANSYS captures more realistic variations, especially under dynamic climatic conditions. These discrepancies directly affect the evaluation of thermal performance and the durability of hemp-clay walls. This study highlights the importance of accurately modeling material interfaces to optimize the performance of geosourced construction systems. It also contributes to validating more representative methodologies to support their integration into sustainable building practices.