In old buildings, which are architectural monuments, the stone three-centered barrel vaults and arches have been often used. In case of reconstruction of old buildings, it becomes necessary to increase the load on these elements. Calculation of additional load is based on instrumental examination of the vaults. While creating an analytical model of a barrel vault, it is necessary to use the experimental results of determination of the vault geometric parameters and material strength characteristics. The vault bearing capacity determined on base of analytical estimation is confirmed by similar calculations done by means of software packages, as well as by the data obtained by means of real loading of the vault. The proposed procedure for determination of additional load onto barrel vault may be also used in designing of similar architectural monuments.