Your neighbour is building.
You have more say than you think.

Normally nothing. Section 11 of the Party Wall etc. Act 1996 puts the cost of the works, and the reasonable surveying fees on both sides, on the building owner, because the works are for their benefit. The two surveyors agree what is reasonable and it is set out in the Award. In the ordinary case an adjoining owner pays nothing at all. There are narrow exceptions, mainly where you ask for work purely for your own benefit or where your conduct causes unnecessary cost, and we will tell you plainly if we think one applies to you.

You can. That is what an 'agreed surveyor' means, a single surveyor acting for both owners. It is quicker and cheaper for your neighbour. Whether it is right for you depends on the works. For a straightforward loft conversion it can be perfectly sensible. For excavation, underpinning, basement work or anything structurally significant, we would generally advise appointing your own, because the agreed surveyor was found and proposed by the person doing the building, and once appointed you cannot rescind that appointment.

Act quickly. Notifiable work started without a valid notice is a breach of the Act, and the courts will grant injunctions to stop it. But that remedy weakens as the works progress and the balance of convenience shifts. In practice the usual route is a firm letter, then a retrospective agreement, with an injunction held in reserve. The important thing is not to wait and see.

Not to the works themselves, in most cases. The Act gives your neighbour rights to do certain things, that is the point of it. What you can do is require those works to be carried out under a Party Wall Award: on defined terms, at defined hours, with your property recorded beforehand and made good afterwards, with access controlled and with a surveyor accountable for the detail. The Act does not give you a veto. It gives you protection, and the protection only works if you use it.

It is a dated photographic and written record of your property taken before your neighbour's work starts. If damage appears later, it is the evidence that decides whether the work caused it. Without one, you are arguing from memory against a contractor's records. It is the single most valuable thing an adjoining owner gets from the process, and it is paid for by the building owner.

Once you have dissented and appointed us, a straightforward Award is usually agreed within two to four weeks, depending on how quickly the building owner's side provides drawings and structural details. Complex excavation or basement matters take longer because there is more to check. Your neighbour cannot lawfully start the notifiable works until the Award is served.

It should not, and a good surveyor works hard to make sure it does not. The Act exists so that neighbours do not have to negotiate structural risk across the garden fence. Appointing a surveyor moves the technical argument off your relationship and onto two professionals who do this for a living. In our experience relationships sour when owners try to sort it out informally and it goes wrong, not when the Act is followed properly.