If building work affects a wall, boundary or foundations shared with a neighbour, the Party Wall etc. Act 1996 almost certainly applies, and notice must be served before work starts. In London terraces and semi-detached houses, that covers most extensions, loft conversions and basements.
Work that needs notice
The Act covers three kinds of work:
- Work to an existing party wall, such as cutting in to insert steel beams for a loft conversion, raising the wall, or removing chimney breasts that form part of it.
- Building a new wall on or at the boundary line, common with side return and rear extensions.
- Excavating near a neighbour's building: within 3 metres and deeper than their foundations, or within 6 metres where the excavation would cut a 45-degree line drawn down from the bottom of their foundations.
How much notice
- Party structure notice (work to a party wall): at least two months before work starts.
- Line of junction notice (a new wall at the boundary): at least one month.
- Notice of adjacent excavation: at least one month.
Notices must be in writing and served on every adjoining owner, which can include freeholders and long leaseholders as well as the occupiers next door. A notice lapses if the work has not begun within twelve months, so serving too early carries its own risk.
After notice is served
The neighbour has 14 days to respond. They can:
- Consent. Work can proceed once the notice period ends. We still recommend a schedule of condition, a record of the neighbour's property before work starts, so that any later damage claim can be settled on evidence.
- Dissent. A single agreed surveyor, or one surveyor for each side, prepares a party wall award setting out how and when the work will be done.
- Not respond. This is treated as a dispute, and surveyors are appointed.
The building owner normally pays the surveyors' reasonable costs.
When to deal with it
At design stage. Party wall timing often sets the earliest possible start date, and an award agreed before the contractor is appointed protects the programme. We identify the notices a project needs at the outset and plan their timing alongside planning and tender, and a well-handled first conversation with neighbours tends to make the formal process smoother.
See our services for house extensions, loft conversions and basements.