Drying and wetting can occur locally at different parts of a building envelope and involve simultaneous heat, air, and moisture transfer. These dynamic wetting and drying processes can be captured using advanced hygrothermal models. In this paper, the one-dimensional hygrothermal model HAMFit is used to simulate the dynamic hygrothermal responses of a sheathing board in a prefabricated wall system. The walls comprise the following layers: fiber-cement board as a cladding layer, plywood as a sheathing board, expanded polystyrene (EPS) as insulation, gypsum board as an interior layer, and 6 mil polyethylene sheet as a vapor and air barrier. The simulation results were compared with measured data from an experiment carried out at the field Building Envelope Test Facility, Building Science Centre of Excellence (BSCE), British Columbia Institute of Technology (BCIT). The model's prediction, using the measured indoor and outdoor boundary conditions, of the transient temperature and moisture content of the sheathing board are in good agreement with the experimental data. This paper presents the simulation parameters, including boundary conditions and modeling assumptions.