The Party Wall Act explained for anyone building next to a neighbour

The Party Wall Act 1996 covers any work that affects a wall shared with a neighbour or a wall on the boundary line. If your work falls under the Act, a formal notice must be served, and you as the building owner pay for it.

Notice is required for: cutting into a shared wall, building a new wall on the boundary line, excavating within three metres of a neighbouring structure below its foundation level, and demolishing or rebuilding a shared wall.

Minimum notice period is two months for wall works and one month for excavation. That is two months before the work is due to start.

If the neighbour consents in writing within 14 days, the process ends there. If they dissent or do not reply, both parties appoint a surveyor. Often each side has their own surveyor, occasionally one shared surveyor is appointed.

The surveyor prepares a Party Wall Award which sets out how the work will be done, protection for the neighbour's property, and how any dispute would be resolved. This is a legally binding document.

Cost: expect £900 to £1,500 per surveyor. On a project where two surveyors are appointed the building owner typically pays for both. Budget £1,500 to £3,000 for a straightforward extension, more for anything complex.