Hi, The slab of my house had just been poured whereas the house on the next lot is already built. As the land has a natural slope, my lot had to be excavated. Therefore it requires a retaining wall of approx 900 mm high, and visible on my side. The fences will be built on the top of this retaining wall. How does the sharing of costs under property law work in this case? Should the cost of the wall and the fences be shared with my next door neighbour? Thanks.