Out of sight, out of mind.
This neighbour constructed a terrace against the back wall of a cottage I was surveying.
They did this without asking permission. They also constructed it in such a way that rain drained off the terrace onto the rear wall. When I went round the damp had started to permeate through the wall and was loosening the plaster and wallpaper.
Not a good situation to start off with your new neighbour!