Party wall notices running alongside a planning application

A party wall notice for an extension has nothing to do with your planning application, and the two programmes still have to be sequenced together. The council has no role in party wall matters, cannot impose them by condition and will not check them. Your neighbour's dissent cannot stop the permission. What it can do is stop the build, and because a party structure notice runs for two months while a planning decision runs for eight weeks, serving the notices at the wrong point in the process is how people lose a summer.

The Party Wall etc. Act 1996 sets three separate notice regimes, each with its own period. Work out which ones apply before you fix a start date.

Why the two processes are separate

Planning permission decides whether the development is acceptable in planning terms. The Party Wall Act decides how works affecting a shared structure or a neighbour's foundations are carried out, and who pays for what if something goes wrong.

They do not talk to each other. A grant of planning permission gives no right to work on a party wall, and a party wall award gives no planning permission. The ownership certificates you sign on the application form relate to who owns the application land, not to party structures.

One practical consequence: a neighbour who objects to your planning application and separately dissents to your party wall notice is running two entirely different arguments, and neither strengthens the other.

Works that trigger a notice

Three sections, three triggers, three notice periods.

Most rear extensions on a semi or a terrace hit at least two of these. Cutting a flashing chase into the neighbour's half of the party wall is section 2 work. So is inserting a beam. So is removing a chimney breast that forms part of a party structure.

Section 6 is the one people miss, because it catches works that do not touch the neighbour at all. A trench for a strip foundation 2 metres from the boundary, going 900 millimetres deep next to a house with 600 millimetre foundations, needs a notice.

Notice periods and how they affect the programme

A notice has a life. Once served, the works must be begun within 12 months and carried on with due diligence, or the notice lapses and you serve again.

That gives you a window rather than a deadline, and it makes the sequencing straightforward once you see it.

1. Submit the planning application.
2. Fix the structural design, including foundation depths and the treatment of the party wall, because the notice has to describe the works accurately.
3. Serve notices once permission is granted and the design is settled, and at least two months before the start date if section 2 works are involved.
4. Deal with any dissent and the award in parallel with discharging pre-commencement planning conditions.
5. Start on site.

Serving before the design is fixed is the common error. A notice describing a 600 millimetre deep foundation, followed by a site decision to go to 1.2 metres because of a nearby tree, needs a fresh notice and a fresh period.

Adjacent excavation and the distance tests

The two section 6 tests are geometric and worth drawing rather than describing.

Section 6(1) applies within 3 metres of a neighbouring building or structure, where the excavation goes lower than the bottom of their foundations. Section 6(2) extends to 6 metres, where a line drawn downwards at 45 degrees from the bottom of their foundations would intersect your excavation.

You need two pieces of information: the horizontal distance to their building, and the depth of their foundations. The second is rarely known. A trial hole on your own side, or a look at any historic drawings, is usually the answer, and where the depth cannot be established the safe course is to serve the notice.

Where the excavation is for a basement or a deep pad, expect the neighbour's surveyor to ask for a movement monitoring regime and possibly for design changes. Proposals to deepen an existing footing attract more scrutiny again. A notice under section 6 must be accompanied by plans and sections showing the site and depth of the excavation.

Dissent, surveyors and the award

The neighbour has 14 days to reply. Consent in writing, and the Act's machinery stops there. Dissent, or no reply at all within 14 days, and a dispute is deemed to have arisen.

At that point one of two routes opens. Both owners can appoint a single agreed surveyor, which is quicker and costs less. Or each appoints their own surveyor, and those two select a third surveyor to resolve any disagreement between them.

The surveyors produce an award under section 10. It records the works permitted, the method, the hours, the access arrangements, a schedule of condition of the neighbour's property, and who pays the fees, which is normally the building owner. The award is binding on both owners and can be appealed to the county court within 14 days.

Budget for this. Two surveyors on a straightforward rear extension is a real cost, and it arrives at the same point in the programme as the contractor's deposit.

Planning conditions that interact with party wall works

Three interactions are worth watching.

Pre-commencement conditions have to be discharged before development starts, and the party wall award may require a change to the approved design. Where the award or the neighbour's surveyor forces a deeper foundation, a moved rainwater pipe or a revised flank detail, the approved drawings may no longer match what will be built. Small changes go through as a non-material amendment under section 96A of the Town and Country Planning Act 1990. Anything that changes the appearance needs a section 73 application or a fresh one.

Special foundations, which the Act defines as foundations using an assemblage of beams or rods to spread the load, cannot be placed on the neighbour's land without their written consent under section 7(4). That matters where an existing party wall footing is to be strengthened with a reinforced raft or a piled solution, because a neighbour is entitled to refuse and the structural design then has to be rethought.

And where the extension crosses a public sewer, the water company's build-over process runs alongside both regimes. Building over a sewer in a back garden has its own approval and its own timescale.

Sequencing notices with the build programme

Illustrative example: a wrap-around extension on a Victorian terrace. Planning permission granted in late March. Structural design finalised in April, with a 1.1 metre foundation next to the neighbour's 700 millimetre footing and a steel beam bearing into the party wall. Section 3 and section 6 notices served on 20 April. Neighbour dissented on day 11. Agreed surveyor appointed in early May, schedule of condition carried out mid-May, award issued at the start of June. Works began on 24 June, four days after the two month section 3 period expired.

Nothing went wrong in that sequence, and the only reason it worked is that the notices were served before the contractor was booked rather than after. The same logic applies to the limits on the design itself, because a scheme drawn to the edge of the Class A allowances has no room to absorb a foundation change.

Two habits help. Talk to the neighbour before the notice arrives, because a letter from a surveyor is the worst possible introduction to a project they have already objected to. And keep the planning covering letter and the planning statement silent on party wall matters, since they are not material planning considerations and raising them invites confusion.

This is general guidance, not legal advice. Party wall matters turn on the facts of each boundary, so take advice from a party wall surveyor and check the planning position with your local planning authority before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.