When planning to build a garden wall, always check the type of soi1 in the garden before starting-work. If the soil is clay, a long-spell of dry weather will inevitably cause the clay to shrink and the wall to crack or even collapse. The only satisfactory solution is to lay the foundation on miniature concrete piles – the system used to support buildings where there is a risk of soil movement.
Dig the trench for the foundation. And then use a hand auger to bore holes into the sub-soil to a