The characteristics and the status of the existing stock of residential buildings are extremely important for the national economy of all countries including Hungary. Formerly some methods and approaches to formally tackle and evaluate individual buildings based on available records and expert reports were formulated. These methods are suitable for the evaluation and ranking of residential buildings and make it easier to complete the status assessment and decision support for further utilization. A mathematical analysis has been conducted to identify the sensitivity of the calculated final results in the case of the applied fuzzy signatures related to the changes of the membership values at the leaves (the end nodes of a graph). This paper briefly presents the methods, then it investigates the validity of these results taking into consideration the possible subjective discrepancy and certainty in the evaluations.