The short answer
Three broad categories of work are notifiable under the Party Wall etc. Act 1996: work to an existing party wall or structure; building a new wall on or at the boundary; and excavating near a neighbour’s building. If your project falls into any of these, you must serve the right notice before starting — regardless of planning permission or permitted development, and even on a detached house where the excavation rules are met.
Why it matters
In more detail:
- Work to the party wall or structure (section 2) — cutting in beams, raising, thickening or rebuilding the wall, removing a chimney breast on it, cutting in flashings, inserting a damp-proof course, or demolishing and rebuilding.
- Building on the line of junction (section 1) — a new wall up to or astride the boundary.
- Excavation (section 6) — within three metres and deeper than the neighbour’s foundations, or within six metres on the 45° line.
So rear, side and two-storey extensions, loft conversions with steels, basements, underpinning, boundary walls on the line and chimney breast removal are all typically notifiable. Work that is usually not notifiable includes jobs that do not touch the party wall or trigger the excavation rules — replastering your own side, fitting a kitchen, or minor internal works. Borderline cases are worth checking before you assume.
What to do now
- If your neighbour does dissent, suggest a single agreed surveyor acting fairly for both of you — cheaper and faster than two. Coburns recommends this wherever possible.
- List exactly what your project involves.
- Map each item to the three categories above.
- Identify every adjoining owner — both sides on a mid-terrace, plus any flats and freeholders.
- Serve the right notice with the correct period before you start.
- If anything is borderline, ask a surveyor before committing to a start date.
Common mistakes
- Assuming planning permission or permitted development removes the duty.
- Assuming a detached house is exempt from the excavation rules.
- Treating chimney breast removal or flashing cuts as “minor”.
- Missing one of the excavation triggers, or one of the owners.
When to call Coburns
Send us your plans and we will tell you, free of charge, exactly what is notifiable, identify all the adjoining owners, and serve the notices for you.