The article covers the building maintenance safety , which depends on design decisions and their implementation in the construction, residual operation time and condition of the object, the rate of the object and the environment changes, serviceability standards and the quality of their implementation during the service life of the object, etc. Ensuring the operation safety is not only technical, but also an economical problem. Aggregate cost of reproductive measures is comparable to the cost of new construction and frequently exceeds it. The research task was mathematical modeling of the growing dynamics of gradual failures of structural components of the building during the operation time based on normative data of Russian design code VSN 53-86(r); the calculation and modeling of the repair costs dynamics as a percentage of the estimated cost of construction works in the value of physical deterioration of structures. The study has found that the numerical value of physical deterioration defined by VSN 53-86 (r) can not be used for estimating the real repair cost, because of its non-compliance with cost of renovation and percentage of components renovation.