JAMES SHEKHDAR wrote:
What factors affect the depth of foundations?


Weight of building above
Soil quality

That's it mainly.

Soil quality breaks down into many tings like localised tree roots,type
of soil,likelihood of flooding etc, etc, plus the depth of anything
sturdy like bedrock in a peat bog.

The aim of the foundations is to spread the load of the building over as
wide an ear as possible onto a layer of sunsoil that is as stable as
possible..so the house sort of 'floats' in the ground.

If there happens to be a lump of rock there, you can build straight off
that. If its a peat bog, you may have to go down t5 meters to find
something solid - pipes is the answer there.