Persian vernacular architecture commonly combines the use of unfired adobe and fired tiles to create intricate vaulted roofing systems. These buildings are vulnerable to seismic loading due to adobe’s weak tensile properties and a building tradition that does not adhere to modern seismic codes. In the city of Kashan, Iran, modular sha’rbafi (silk-weaving) workshops – a subset of vaulted vernacular structures – are semi-subterranean, being partially built into an earthen foundation. The city is located on a tectonic fault, so there is concern for the structural stability of the workshops. The present work uses nonlinear finite element analysis to evaluate the structural behavior of these vaults under static and dynamic loads. The results help to evaluate the conditions leading to collapse and to define a terminus post quem of construction for the workshops, based on whether or not the structures could have survived Kashan’s last major earthquake in 1778. Evidence of silk-weaving in Kashan dates to the 16th century, but the dating of these workshops is debated. Architectural surveys provide the basis for creating a generalized module of a vaulted sha’rbafi workshop. Material properties of unfired adobe and fired bricks were estimated from published studies of adobe structures in Iran. 2D plane strain and 3D models were analyzed with Abaqus/CAE Explicit, and the materials were implemented with the concrete damaged plasticity and Mohr-Coulomb formulations. Results indicate significant structural contribution of the vault’s fired brick intrados and semi-excavated foundation condition to both the static and the dynamic response.