The invention provides a kit of structural building elements for rapid erection and assembly to form a living space having a ridged roof, wherein the elements (1, 2) are linked together and comprise a central prism-like element (1) and corresponding outer elements (2), said elements being arranged so that in a first state, suitable for transportation, they form an essentially cuboid structure having overall dimensions not equivalent to those of a standard 40 foot freight container and, in a end, erected state, the outer parts are raised to form a roof ridge line (3). Erection of a prefabricated building using the kit of parts can be effected without the need for heavy lifting machinery by pushing the outer elements (2) inwardly so that they slide up the sloping faces of the prism like central part.