Section 168(4) in West Bengal Municipal (Building) Rules, 2007
(4)The foundations of all buildings or parts must rest on solid ground or rock and have width and depth suitably designed according to the distribution of the soil and hard rock strata in different parts of the foundation and have dimensions worked out "as per the permissible safe bearing capacity and other consideration in accordance with relevant Codes of Practice of BIS. The depth below the ground level shall not be less than 2.0 metres in the case of R.C.C. Column footings and 1 : 2 metres in the case of all other foundations.
