How much should be the depth of foundation of RCC Boundry Wall?

1. Availability of adequate bearing capacity & dead load of the the wall.2. Depth of shrinkage and swelling in case of clayey soils, due to seasonal changes which may cause appreciable movements.3. Depth of frost penetration in case of fine sand and silt.4. Possibility of  excavation close by 5. Depth of ground water table 6. Practical minimum depth of foundation should not be less than50 cm. to allow removal of top soil and variations in ground level. 7. Hence the best recommended depth of foundation is from1.00 meter to1.5 meter from original ground level.