Floating foundation

A casting kit for constructing a foundation, the casting kit comprising:

• a plurality of void forming members, each of which has a securing element on at least one side to secure the void forming member to a securing element of a matched void forming member thereby to define a minor void forming formation, wherein the minor void forming formation is defined by four void forming members secured to one another with step formations between the void forming members forming a cross-shaped groove running across a top face of the minor void forming formation, and wherein, in use, a first set of tensile elements and settable material are received in the groove to form supporting ribs;
• a spacer shaped and dimensioned to secure the four sets of four minor void forming formations to one another while maintaining a gap between adjacent sets of four minor void forming formations to define a major void forming formation, wherein, in use, a second set of tensile elements and settable material are received to define stiffening ribs in the major void forming formations;
• and
• shuttering that, in use, is arranged around the major void forming formations to create edge beams in a foundation site when settable material is cast around the major void forming formations.