Despite the widespread use of recycled steel in construction, the industry still has difficulty meeting the net zero CO2 emission goals due to the significant gray energy losses during building demolition and recycling. Thus more emphasis has been put on re-using construction material with the help of design for disassembly. The application of visible steel in residential construction (especially in Switzerland) has been limited due to fire protection regulations and the challenges associated with practices to address this matter. Concrete-steel hybrid structures, commonly used for fireproofing steel structures, come with high CO2 emissions and lack easy dismantling, rendering them not compatible with sustainability goals. Furthermore, with hybrid steel-wood systems, the composite action is often not well developed, leading to inefficient use of material. The authors have introduced a demountable folded steel and cement-free concrete composite system that meets the fireproofing requirements and reduces the gray energy and raw material. The additively joined construction facilitates the later reuse of the elements. The structural system features small-scale steel beams and columns designed for residential buildings, using standardized components. The system’s modularity supports architectural flexibility and adaptability for new constructions and extensions. This paper focuses on the details and development of joints and connections within this system that allow easy and efficient assembly and disassembly process, promoting circular economy in the construction and therefore playing a crucial role in improving the sustainability aspects and structural integrity of the hybrid steel structures.