FIG. 3.4 SIMPLE ISOLATED FOOTINGS OF LIGHTLY LOADED COLUMNS.
The value of offset a may vary from 10 to 20cm. As a thumb rule, the base dimensions of the concrete base should not be less than twice the appropriate lateral dimension of the column in that direction. The thickness of concrete block should atleast be equal to a in the case of cement concrete and 3/2 a in the case of lime concrete base.