If the Building Owner is doing work on or to a party structure (wall, floor, or fence wall) or digging within the prescribed depths and distances without serving Notices, he is acting outside the law and can be stopped. If you are certain that he is acting in a way that requires action under the Act but has not followed it, you should seek an injunction from the County Court. You should take legal advice first but the procedure is fairly simple. You will apply for Interlocutory Relief. This is heard in chambers and you tell the Judge what is happening and ask him to grant an injunction. He will require the Adjoining Owner to give the “usual undertakings” or cross-undertakings in damages. This means that if you have got it wrong, your rights have not been infringed and the Building Owner is put to costs because of the injunction, you will bear those costs. Think about it carefully.
If you are a Building Owner and are served with an injunction, STOP! If you do not you could be imprisoned for contempt. Only continue if you are absolutely certain that what you are doing is not covered by the terms of the injunction. Again, you should take legal advice to be sure of your position. The risks really are not worth taking a chance.