Width of Foundation

It is acquired through dividing the total load per unit length on the foundation bed by the safe bearing capacity of the soil.

Let      w = total load in kN per m, and

q = safe bearing capacity in kN/m².

∴          Width of foundation = (w/q) m                                                                . . . (1.1)

In order that the wall may be stable, the lowermost course of the wall footing is made twice the width of the wall (T) and the concrete bed block is made to extend at least (j) 10 to 15 cm on either side of the lowermost course,

Hence, the width of foundation

 = 2T + 2 j                                                                                                        . . . (1.2)

The maximum value obtained from Eqs. (1.1) and (1.2) should be adopted as the final width of foundation.