Does the Party Wall Act apply to your project?
These works usually trigger the Act — building at the boundary, working on an existing party wall, and excavating close to a neighbour’s building. The guide below is a rough starting point, so please check with us before serving a notice or starting work.
The three triggers
If your work matches any one of these, the Act is engaged.
Building on the boundary line
You’re putting up a new wall on or right up to the boundary with next door, where there’s currently no building — or only a boundary wall.
- A new extension wall built hard against the boundary line
- A new party wall built astride the boundary, with the neighbour’s agreement
- A new garden or boundary wall placed on the line of junction
Work on an existing party wall
You’re working directly on the shared wall or structure itself — cutting into it, changing its height, or altering how it performs.
- Cutting in to take beams for a loft conversion or steel frame
- Raising, lowering, underpinning, or rebuilding a defective party wall
- Removing a chimney breast, inserting a damp-proof course, or weatherproofing a wall exposed by demolition next door
Excavating near a neighbour
You’re digging close to a neighbouring building or structure, deep enough to affect the ground supporting it.
- Digging within 3 metres of a neighbouring building and going deeper than their foundations
- Digging within 6 metres where a line drawn down at 45 degrees from the base of their foundations would be cut by your excavation
- Basement digs, underpinning, and deep foundations for a rear or side extension
What counts as a “party wall”
Party wall
A wall astride the boundary that forms part of a building — or a wall standing on one owner’s land that both owners use to separate their buildings.
Party fence wall
A freestanding wall astride the boundary that isn’t part of a building, such as a masonry garden wall. Ordinary timber fences don’t count.
Party structure
The same idea applied to floors and partitions separating flats or units that are in different ownership.
Adjoining owner
Not just the freeholder next door. It also covers leaseholders whose lease exceeds one year, anyone under contract to buy the property, and anyone entitled to receive rent from it.
What usually doesn’t need a notice
Plenty of work is simply out of scope.
Find out if the Act applies to your project
01 Are you building a new wall on, or right up to, the boundary with a neighbouring property?
02 Are you working directly on a wall or structure you share with a neighbour?
03 Are you excavating within 3 metres of a neighbouring building or structure?
Not sure where your project fits?
If your situation doesn’t fit neatly into these categories, talk to a surveyor. We’ll tell you straight whether the Act is engaged.