Do you need a party wall agreement? Run your project through this 60-second checker. If you answer yes to any question below, your work is probably notifiable under the Party Wall etc. Act 1996 — which means notices first, and an agreement (award) if a neighbour dissents.
The 5-question checker
- 1. Are you cutting into, raising, thickening, underpinning or demolishing a wall shared with a neighbour? (Loft conversion beams and chimney breast removal count.)
- 2. Are you removing a chimney breast on a wall between you and next door?
- 3. Are you building a new wall at or astride the boundary line?
- 4. Will you excavate within 3 metres of any neighbouring building, deeper than its foundations? (Most extension footings do.)
- 5. Will you excavate within 6 metres, deep enough to cut a 45° line drawn down from the neighbour's foundations? (Basements, piling.)
All five “no”? Your work is unlikely to be notifiable — see the reassurance section below. Any “yes”? Read on.
Project by project: when do you need a party wall agreement?
Loft conversion — almost always in terraced and semi-detached homes: steel beams bear into the party wall (two months' notice). Rear extension — usually: footings within 3 metres of next door's structure, sometimes a wall astride the boundary (one month). Basement — always, and with the most care: deep excavation triggers the 3m and 6m rules, and awards typically require method statements. Garden wall on the boundary — yes if astride the line; a wall wholly on your land needs no agreement (only excavation notice if within 3m and deeper than the neighbour's footings). Internal knock-through of a party wall — yes. Detached house — the Act still applies to excavation near the neighbour's structure; detachment doesn't exempt you.
When you genuinely don't need one
Plastering, shelving, electrical sockets, removing chimney breasts on internal (non-shared) walls, replastering damp walls, new floor coverings, and garden fences (timber fences aren't party structures). Minor works that don't affect the wall's structure need no notice — and anyone who tells you every job needs an agreement is selling, not advising.
What happens if you skip it?
Starting notifiable work without notices exposes you to an injunction stopping the build, removes the Act's protections, and leaves any damage claim to be fought in court rather than settled cheaply on surveyor evidence. And it follows the property: missing paperwork surfaces in conveyancing — see selling a house with no party wall agreement.
Next steps
Notifiable? Serve valid notices — our party wall notice guide explains the three types, or read the full Party Wall Act 1996 guide and who owns a party wall. Our RICS surveyors — including a dedicated party wall surveyor in London team — serve notices within 2–3 working days.
Still unsure? Describe your project and we'll tell you in one free phone call — 0204 579 8270 or get a fixed quote.
