Party Wall Notices: Types, Timing and How to Serve Them

Last updated: August 2026 · Verified against current government planning rules and London council records.

When do you have to serve a party wall notice?

Quick answer: Before starting any work the Party Wall etc. Act 1996 covers. Work on a shared structure needs a party structure notice served two months before you start; building a new wall at the boundary or excavating near a neighbouring building needs one month. Your neighbour then has 14 days to respond, and no response counts as dissent, not consent. The notice is entirely separate from planning permission — you can need both, either or neither.

Almost every extension we build in North London triggers at least one notice. The housing stock guarantees it: a Victorian terrace in Haringey or Islington shares a structural wall on both sides, a 1930s semi in Barnet or Enfield shares one — so cutting in steels, building along the boundary or digging new foundations all bring the Act into play. This guide covers the three notice types, what each must contain to be valid, and the timing that stops the Act delaying your build. For the wider process, start with our full party wall guide.

What are the three types of party wall notice?

The Act deals with three situations, each with its own notice and notice period. Which you serve depends on the structural work, not the size of the extension — and one project often needs more than one. A rear extension on a mid-terrace Victorian house in Islington can need all three: steels into the party wall, a new flank wall on the boundary, and foundations within 3m of both neighbours.

Notice type	Act section	Notice period	Common trigger
Party structure notice	Section 2	2 months	Cutting steel beams into the shared wall of a terrace or semi; raising a party wall for a loft conversion
Line of junction notice	Section 1	1 month	Building the flank wall of a side return or side extension up to or astride the boundary
Notice of adjacent excavation	Section 6	1 month	Digging extension foundations within 3m of a neighbouring structure and deeper than its foundations

The section 2 notice is what most people mean by "party wall notice" — it covers work on the shared structure itself: inserting beams, underpinning, raising or rebuilding the wall. Section 1 covers a new wall built where none exists, the standard trigger on side returns. Section 6 covers excavation within 3m of a neighbouring structure and deeper than its foundations, or within 6m where a 45-degree line from their foundations would cut through your dig. Victorian terraces sit on shallow footings, so a modern foundation trench next door almost always qualifies.

What must a valid party wall notice contain?

The Act sets no prescribed form, but a notice missing the required content is not a notice at all. Every notice needs the building owner's full name and address — all names, if the house is jointly owned — the address of the property being worked on, a description of the work clear enough for the neighbour to understand what is planned, and the intended start date. It must be dated, and a section 6 excavation notice must also include drawings showing the position and depth of the dig relative to the neighbouring building.

Identifying who to serve takes more care than people expect. Notices go to every adjoining owner, and "owner" includes long leaseholders as well as freeholders — so a converted Victorian house in Camden with a flat against your party wall can mean serving both the leaseholder and the freeholder. On a mid-terrace you are usually serving both sides. A wrong name, or a missed owner, is one of the most common ways notices fail.

What can your neighbour do once the notice is served?

They have 14 days to respond, and there are three possible answers. They can consent in writing — the process ends there and costs nothing beyond the notices. They can dissent and appoint their own surveyor, starting the two-surveyor route. Or they can dissent but agree to share a single "agreed surveyor", which settles the same questions with one professional instead of two.

Silence is the outcome that surprises people: no response within 14 days counts as dissent and triggers the surveyor process just as an active refusal would. Dissent is not a veto — the surveyors settle how the work proceeds, not whether it does, and record it in a party wall award. We cover what the award contains and what surveyors decide in our guide to how a party wall agreement works. Where surveyors are appointed, budget £1,000 to £2,500 per affected neighbour; the building owner — the person doing the work — pays. A normal notice-to-award timeline is six to ten weeks.

Why do defective notices restart the clock?

An invalid notice is void — legally, it was never served. The 14-day response window never opened and the notice period never started running. The painful part is when you find out: usually weeks in, when the neighbour's surveyor examines the notice and rejects it. You re-serve a corrected notice and every clock restarts from zero, which on a party structure notice hands back the full two months.

The usual defects are simple: a missing joint owner's name, no start date, a work description too vague to assess, or a section 6 notice served without the drawings the Act requires. That last one is the most common on extensions, which is why we get the extension drawings to a servable standard — plans and sections showing foundation position and depth — before any notice goes out.

When should you serve a party wall notice?

During the planning period, not after it. A householder planning application takes eight weeks from validation to decision, and the longest notice period is two months — near enough the same length. Serve your notices the same week the planning application goes in and the clocks run in parallel: by the time Barnet or Enfield issue a decision, your notice periods have expired and any surveyor process is well under way. Serve after the decision instead and the Act becomes the critical path, adding up to two months of dead time before a spade hits the ground.

The caveat is that a notice must describe the work you will actually do, so it needs settled structural intent — another reason to finalise drawings early. And the two regimes never talk to each other: planning permission does not imply party wall consent, and a signed award does not imply planning permission. We serve notices for clients as standard and run the party wall clock alongside the planning application on every job that needs it — part of the process when you book a free site visit, not something to arrange yourself.

Frequently asked questions

Can I serve a party wall notice myself?
Yes — the Act does not require a surveyor to draft or serve notices. The risk is validity: a defect voids the notice and restarts the clock weeks later. We serve notices for clients as standard.

What happens if my neighbour ignores the notice?
After 14 days, silence counts as dissent and the surveyor process begins. A surveyor can be appointed on their behalf if they refuse to engage — a neighbour cannot block the work by ignoring it.

Can my neighbour use the Act to stop my extension?
No. Surveyors decide how the work proceeds — hours, protections, access, making good — not whether it proceeds. Objections to the principle of the extension belong to the planning process, which is separate.

Do I need notices if my extension is permitted development?
Yes, if the work falls within the Act. A 3m rear extension needing no planning application still needs an excavation notice if you are digging within 3m of next door and deeper than their foundations.

Does the Act apply to flats?
Yes — work on the structure between two flats is covered, and you may need to serve both the leaseholder and the freeholder next door. The planning side differs too: flats and maisonettes have no householder permitted development rights at all.

How much does the party wall process cost?
If your neighbours consent in writing, nothing beyond preparing the notices. Where surveyors are appointed, budget £1,000 to £2,500 per affected neighbour, paid by the building owner — worth planning for on a mid-terrace with dissent on both sides.