Abstract: The invention relates to a constructional system for frames, racks and casings and in particular for sub-racks and equipment cabinets for accommodation of electrical and electronic assemblies, units and printed circuit boards.At least one joint system having engagements is provided for thread-forming screws as fastening elements for particularly cost-effective manufacture of such type of constructional systems, and for simple assembly as well as for ensuring effective EMC screening in accordance with the invention between horizontally and vertically arranged components, in particular between side parts and a top part and a base part having multi-folded horizontal struts and/or vertical struts.