Every landowner has a ‘duty of care’ not to use his or her land in a way that causes damage to a neighbour’s property. Major headaches can occur when it comes to the likes of earthworks and excavation being carried out.
As a landowner you have “the right of support for the land in its natural state” or in other words, no-one next to you or above or below you should do anything to their land that affects the stability of yours. This includes the likes of excavation and drawing off underground water or silt. Go and whip out that retaining wall at your peril!
It’s important to note though that where land is unstable, an adjoining landowner does not usually have a duty to stabilise it. Only a duty not to remove any support already present. If a landowner replaces a natural support with an artificial support - there’s no liability. Nor is there if a support like a retaining wall is removed by natural causes like a flood.
However the situation could be very different if something on your property that is not well maintained falls and damages a neighbour’s property – a tree for example. Particularly if that neighbour had previously complained about it.