A building element includes an upper side, a lower side, at least one first lateral face, and at least one first end face, where the at least one lateral face is formed with a longitudinal lateral groove such that a longitudinal upper grove edge and a longitudinal lower groove edge are formed. The upper groove edge has a toothed shape. A building includes one or more load bearing elements, and a plurality of building elements connected to respective load bearing elements. A method of joining building elements and load bearing elements in a building includes providing the load bearing elements with a not-cast upper part, putting up the load bearing elements, arranging two or more double T building elements therewith, pulling the telescoping elements, and cast filling the joints between the building elements and the upper part of the load bearing elements such that a smooth surface is formed.
