The service life and the durability of wood-based structures is closely related to the moisture content of the material. In order to establish an optimal and reliable evaluation of the moisture content distribution, this paper presents an experimental–numerical approach based on the adaptation of Electric Resistivity Tomography, mainly used for electrical prospecting measurements in geophysics. This method is based on the injection of electric current and the measurement of the potential difference using needle-shaped probes inserted into a Douglas-fir sample. Electrical measurements were coupled to a numerical finite-element-based approach. A numerical inversion was sequentially performed to minimize the gap between simulations and experimental data. The result of this study proposes an efficient mixed approach to identify a longitudinal resistivity profile during the wood moistening process. The correlation of moisture content with electrical resistivity offers guidance in the identification of the moisture content distribution of timber elements.