If your new build means a wall on the boundary line, give your neighbour notice first. The same goes for digging near their building below its foundation level. Serve it at least one month before you start. Planning permission or building regulations approval does not remove the need for it.
Time it well, because a notice runs out after one year. Serve it close to your planned start date. Your neighbour can agree in writing, disagree, or not reply. No reply within fourteen days usually counts as a dispute. You can only start before the notice period ends if they agree in writing.
If it comes to a dispute, you can share one agreed surveyor or each appoint your own. If those two disagree, they choose a third. The surveyors write up an award covering the work, when it happens and how. It often includes a record of your neighbour's property. You'll usually cover the surveyor fees, yours and your neighbour's. Your neighbour can't stop the work, but they can have a say in how and when it happens.
Getting notice right early saves you the risk of a court injunction, which can follow if work starts without it. Ring me before you fix a start date on a plot next to someone else's home. At Mitchell & Andrew Building Services I build new builds across Truro, and I'd rather the paperwork is right before a spade goes in.
