Three years ago I had my path flagged, and I have had to get the builder back because it’s sinking. He says if he has to re-lay it I will have to foot half the bill. Do I have any legal right to ask him to do the job again solely at his own expense?
It depends why the path is sinking, and whether it’s the builder’s fault. You should establish the cause of the problem before doing anything more, otherwise you could be faced with another sinking path three years from now! You have to decide whether the builder did a “reasonable” job: would another builder have done more for the amount you paid? It would be unreasonable, for instance, to have expected the builder to put in metre-deep foundations for a path.