Building system

A building system for erecting a building structure, the building system comprising:

• a plurality of precast transportable concrete wall panels;
• each wall panel comprising a reinforcement structure and a plurality of cast-in connecting inserts, each connecting insert being located at a predetermined position;
• a precast transportable concrete floor panel, the floor panel also comprising a reinforcement structure and a plurality of cast-in connecting inserts, each being located at a predetermined position, the floor panel further comprising a recess along at least a portion of a perimeter of the floor panel;
• and
• a precast transportable concrete roof panel comprising a reinforcement structure and a plurality of cast-in connecting inserts for connecting the roof panel to the wall panels, each connecting insert being located at a predetermined position;
• wherein the building system is configured such that when each precast wall panel is positioned in a substantially upright position in the recess of the floor panel and the roof is positioned on top portions of the plurality of wall panels,
• wherein connecting inserts of two adjacent wall panels align so that the panels can be connected using a plurality of mechanical fasteners,
• wherein the roof panel comprises a recessed area configured such that a projecting flange is formed extending on each side and along a perimeter of the roof panel such that when the recessed area of the roof panel is supported on the top portions of the plurality of wall panels, the projecting flange extends along and parallel to an external surface of the top portions of the wall panels, and
• wherein when the building structure is erected, an external surface of the roof panel is inclined thereby forming a slope, an angle of the slope being defined by an angle of the projecting flange relative to the external surface of the roof panel.