Method of constructing a foundation for buildings

DETAILED DESCRIPTION I claim: 1.
In a method of constructing a stiffened raft foundation for a building which includes forming in the ground a grid of intersecting foundation trenches, the grid being made up of two sets of substantially parallel trenches, each trench of each set intersecting at least one trench of the other set; continuously casting settable material within the trenches to obtain an integral grid of intersecting foundation beams; and continuously casting a covering of settable material over the beams and integral therewith, to obtain a slab covering the ground between the beams and having a flat upper surface, the improvement of forming the trenches such that the spacing between adjacent parallel beams of the grid is 1 to 2 meters, and the width of each foundation beam is 100 to 170 mm.
2.
A method as claimed in claim 1 wherein the spacing between adjacent parallel trenches and beams of the grids is 1.
3-1.
7 meters.
3.
A method as claimed in claim 2 wherein the vertical spacing from the bottom of each trench to the flat upper surface of the slab is 300 to 1500 mm.
4.
A method as claimed in claim 3 wherein the thickness of the covering slab is 75-125 mm.
5.
A method as claimed in claim 1 wherein forming the grid of intersecting foundation trenches is such that they are substantially rectangular in cross-section so that the cast beams each have a pair of laterally spaced vertical side faces and a horizontal lower face, the method including the step of reinforcing each foundation beam by embedding a reinforcing bar therein and by embedding a reinforcing bar in the slab above the beam at a position centrally above the beam, the bar in the beam extending parallel to the beam in the interior thereof along the length of the beam midway between the side faces of the beam, and the bar in the slab above the beam extending along the length of the beam parallel to the bar embedded in the beam, each bar being spaced by at least 50 mm from the outer surface of the cast foundation.
6.
A method as claimed in claim 5 wherein each of the bars has a cross-section which has an area which is from 0