Abstract: The invention relates to a fold-out prefabricated construction structure and method for the assembly thereof. The structure, having bays of desired width, length and shape, is made up of porticos formed by pillars and an upper structure (27). The method involves positioning the base (1) on a surface (28) and provisionally fixing at least one portion of said base. This allows opening the porticos with the help of auxiliary structures created for this purpose (14). The elements of the structure are fixed to one another, and to the surface of the portions of the base in their final position. Each of the porticos not yet fixed must be moved to their final position, in a successive manner and separately from the closest fixed portico, together with the rest of still free attached porticos, and suitably fixed to the surface.