The objective of this paper is to evaluate the acceptable differences limit between analytically and experimentally identified modal parameters and to assess its contribution to the success of finite element model updating. To achieve this aim, three one-story reinforced concrete buildings consisting of raft foundation, columns and beams were simultaneously constructed under laboratory conditions. Experimental measurements were taken for each building to determine the modal parameters using ambient vibration tests. All parameters, which could be expected to affect structural behavior, such as structural dimensions, concrete properties, reinforcement detailing, construction joints, concreting days, workmanship, temperature and humidity, were made the same, as far as possible, for each building to eliminate the influence of environmental effects on experimental measurements. At the end of the study, the differences in the experimentally identified natural frequencies were obtained between 3.14% and 11.83%, with all parameters the same for each building model. As a result of this paper, it is suggested that the maximum acceptable differences limit can be taken as 5%.