The function of a space in a building greatly depends on the position of that space in its general configuration system and its desirable performance occurs when the space in relation to other parts of the building can meet the expectations of its users. This topic is known in the literature for functional efficiency. For this purpose, the present study by selecting 18 homes of the Qajar period in Tabriz has analyzed the functional efficiency changes of these houses in line with their structural-spatial transformations. The quality of access in this study, known as the independent variable, was measured in terms of four indicators of permeability, flexibility, spatial integration, and relation between components, and the impact of each of these indicators on the functional efficiency of the houses was analyzed. The results of the research indicated that high-quality accessibility indexes were found in homes built in the early and mid-Qajar period, However, at the end of the Qajar period, these indicators declined, the most important factor in this regard is chaning the architectural system from introverted to extroverted and changing the function of the courtyard from a server space to a mere passageway space.