Boundary Wall design for clay soil on a hill

Hi Gilly. Clay soil as a bearing surface for structures inc. garden walls etc. Suffers from changes in volume when moist/dry etc. This causes it to ‘heave’ and crack the structures that are built on it. Clay soil deeper down in the ground is less susceptible to moisture changes and so tends to stay the same volume and hence doesn’t shrink/expand and ‘heave’ If you want a boundary wall that won’t crack, built on clay, you need to dig a deep enough footing. 1 metre is usually sufficient, providing that there’s no significant vegetation close by. Trees and shrubs have a water demand via the roots, and this can cause even deep strata of clay to suffer shrinkage/expansion. Sorry, but there’s no cheap solution. Strengthening a wall built on shallow foundations will just move the cracks to the weakest point in the wall.

If I understand correctly the wall is failing or bellying as we say and you want to extend the life or put a fence in front! Ok my resolve would be to sink so 8ft sleepers (8"x4") as deep as possible set in concrete. These should last 25 plus years, strengthen the wall AND allow you to fix a new fence to them 👍