The main idea of the proposed method is to increase the load-bearing capacity of vaults as well as their seismic resistance by replacing heavy gravel topping with a reinforced, light-weight foam-concrete topping, connected to the surrounding walls by steel anchors. Two of vaults with a gravel and foam concrete topping have been tested by applying increasing vertical loading and two of them by applying cyclic horizontal loading. A significant increase in load-bearing capacity and stiffness has been observed as well as improvement in the mechanism of behaviour of masonry vaults subjected to the vertical and horizontal loading.