In solving problems associated with maintaining buildings in good condition, it is important to recognise the changes in op-
IntroductionIn business planning of repairing the buildings one should determine the scope of works. There is no reliable mathematical models that allow the estimation of the operational reliability of a building, often referred to as changes in the building performance. In the case of technical appliances (mechanical and electronic) attempts are undertaken to determine the prediction of their operational reliability, but for buildings -only indicative graphs of changes in performance are presented. The method of behaving and changing the reliability of the building throughout its use will be useful in planning renovations.All appliances are built from parts. Similarly, each building consists of many components. These elements, which fulfil different functions, are made of dissimilar materials, each has different properties, and different durability periods. In order to determine building reliability it is divided into components which are analysed, first separately and then altogether in the entire building. In the process of predicting the reliability of both individual components of a building and a building as a whole, it may be initially assumed that the lifetime of a building is a 100-year time interval.To model a situation for the needs of the survival analysis, when the probability changes in time, the Weibull distribution is most frequently used as a distribution of random variable of the time of the building's usefulness. The probability of the exploitation of a building without any breakdowns in a given period of time is defined as exploitation reliability.