Abstract: A building construction and method of constructing a building including at least a lower level and a roof permits elevation of the roof of the original building as a unitary structure to a sufficient additional height to enable an additional level to be constructed intermediate the lower level and the raised roof. Vertically extendable stabilizing members are installed in the original building structure and are later used to support the roof structure after raising it so that an additional floor level can be built over the original level without destruction of the original roof or building of a new roof. Hydraulic ram devices may be used to raise the roof.