These have been set out in The Party Wall etc Act 1996. Put simply, you must notify your neighbour and gain approval before carrying out building work, which affects a party wall, or excavations near party walls.
The Act is there to protect all property owners from potential issues that that could arise from proposed works to a property. It enables owners to carry out works whilst protecting adjoining owner’s rights and avoiding unnecessary inconvenience. It avoids or minimises serious disputes by making sure property owners notify their neighbours in advance of certain proposed works.