What Is a Party Wall Agreement?

A party wall agreement, or award, is a formal arrangement required before carrying out certain work affecting a wall shared with a neighbour, or excavation close to their building.

When it applies

Broadly three situations: work on a shared wall, building on the boundary line, and excavation near a neighbour's building.

The excavation rules are the ones people miss. Notice is required where you excavate within 3 metres of a neighbour's building and go deeper than their foundations, both tests must be met. A second rule catches deeper work within 6 metres, where the excavation would cut a line drawn down at 45 degrees from the bottom of their foundations.

Most extension foundations are around a metre deep, which is frequently deeper than an older neighbouring property's. Basements almost always trigger the Act.

It applies regardless of whether you need planning permission. Terraced and semi-detached properties are the common cases.

Why to start early

Notice periods are meaningful, weeks, not days. Projects are routinely delayed because notices were served late, and a builder ready to start cannot.

If your project might involve it, deal with it while drawings are being prepared, not when scaffolding is booked.

What it involves

You serve notice on the affected neighbour. They may consent, or appoint a surveyor. If surveyors are appointed, they produce an award setting out what may be done, how, and recording the condition of the neighbour's property beforehand.

That condition record protects both sides. It is the evidence if damage is later alleged.

Who pays

Generally the party carrying out the work, including the neighbour's surveyor's fees where one is appointed.