The Party Wall Act: a complete guide

The Party Wall etc. Act 1996 gives you the right to do certain work to a shared wall or near a neighbour's building, provided you tell them first. Three sections trigger a notice: section 1 for building on the boundary line, section 2 for work to an existing party wall, and section 6 for excavating close to their foundations. The notice period is two months for section 2 work and one month for sections 1 and 6.

That last sentence is where most guidance goes wrong. Plenty of pages say "two months" flat, which is correct for cutting into a party wall and wrong for digging foundations.

What the Act actually does

It is permission-granting, not permission-seeking. That distinction is the thing to hold onto.

The Act gives you rights you would not otherwise have. Cutting into a wall you only half own, raising it, underpinning it, or excavating so close to next door that you could undermine them, would all be trespass or nuisance at common law. The Act makes them lawful, on condition that you follow its procedure and make good any damage.

So your neighbour is not being asked to approve your project. The government's own explanatory booklet puts it plainly: an adjoining owner cannot stop someone exercising the rights the Act gives them. What a neighbour can do is disagree about how the work is done, and the Act provides a mechanism to settle that.

None of this has changed recently. The Act is unamended, and the GOV.UK booklet was last substantively updated in May 2016. So a 2026 guide and a 2016 guide should say the same thing, which is worth knowing when you are weighing up advice you find online.

The three triggers, and the notice period for each

Section 2 is the long one. Section 3 requires two months' notice before you begin, and section 2 lists the rights: underpinning or raising a party wall, cutting into it to take the bearing of a beam, cutting away a projecting chimney breast, jamb or flue, inserting a damp-proof course, and exposing a party wall that was previously enclosed.

Sections 1 and 6 are one month. Same Act, different clock. If you serve a single letter covering an extension that both digs new foundations and cuts a beam into the party wall, the two-month period governs your start date, because you cannot begin any part of the notifiable work until the longest applicable period has run.

Section 6, the one people miss

If you are building an extension with new foundations, section 6 is probably your trigger, and it is more demanding than section 2 in several ways.

The 3 metre rule. Section 6(1) applies where you excavate within 3 metres horizontally of a neighbour's building or structure and the work will go deeper than the bottom of their foundations. Both limbs have to be met. Shallower than their footings, and you are outside it.

The 6 metre rule. Section 6(2) applies within 6 metres horizontally where the excavation will meet a plane drawn downwards at 45 degrees from the bottom outer corner of their foundation. In practice: the deeper you dig, the further away you can still catch it.

Four things about section 6 that section 2 does not do:

Plans and sections are mandatory. Section 6(6) requires you to serve them with the notice, showing the site and depth of the excavation. A bare letter is not a valid section 6 notice.

It has its own dissent clock. Section 6(7) deems a dispute to have arisen if your neighbour does not consent within 14 days. You never need to rely on section 5 for excavation.

Your neighbour can require underpinning at your expense. Section 6(3) lets them ask you to strengthen or safeguard their foundations, and you pay.

It catches neighbours with no shared wall. Section 6(4) deems people adjoining owners for these purposes even where nothing is shared. Your rear neighbour, whose garden backs onto your extension, may need a notice, and almost nobody thinks to serve one.

A section 6 notice also lapses if you do not start within 12 months, under section 6(8). Serve too early and you serve again.

For where foundations and party wall obligations sit against the rest of an extension budget, our guide to extension costs and the fees nobody quotes sets out where they land against the build.

Silence means different things in different sections

This is the trap, and no page we found while researching this article mentions it.

Under section 5, if your neighbour does not respond to a section 3 notice within 14 days, a dispute is deemed to have arisen. Silence is dissent. Their inaction does not let you proceed unopposed, it pushes you into the surveyor process.

Under section 1(4), silence has the opposite effect. If you serve notice to build a wall on the line of junction and your neighbour does not consent, you do not get a deemed dispute, you lose the right to build astride the boundary. The wall must then go wholly on your own land, at your own expense.

So the same fortnight of a neighbour ignoring your letter produces two entirely different outcomes depending on which section you served under. Read which one you are in before you interpret the silence.

What happens when there is a dispute

A dispute under the Act is procedural rather than adversarial. It is the normal state of affairs, not a falling out.

Once a dispute is deemed to have arisen, section 10 takes over. Either both owners appoint a single "agreed surveyor", or each appoints their own and those two select a third to hold in reserve. If your neighbour refuses to appoint anyone, section 10(4) lets you appoint on their behalf after ten days.

The surveyors then produce an award: a document setting out what work is permitted, how and when it will be done, the condition of the neighbour's property before it starts, and who pays for what. That schedule of condition is the part that protects both of you, because it is the reference point if damage is alleged later.

Costs are determined by the surveyors under section 10(13), not automatically borne by you, though in practice the party doing the work usually pays. There is a 14-day right of appeal to the county court under section 10(17).

The practical read: an agreed surveyor is faster and cheaper than two, and it is worth asking your neighbour to consider one before positions harden. Our guide to party wall notices, awards and what surveyors charge covers the fees and the timeline in detail.

What happens if you just do not serve notice

Here is the uncomfortable answer, and it cuts both ways.

The government's guidance states, repeatedly, that the Act contains no enforcement procedure for failure to serve a notice. There is no penalty, no regulator and no council department that polices it. The only offence created by the Act runs in the other direction: obstructing someone lawfully exercising a right of entry.

That does not make it safe. It means enforcement falls entirely to your neighbour, through the courts. They can seek an injunction to stop the work, which is the real risk, because an injunction can halt a live site. And without the Act's protection you lose its defence, so you are exposed to ordinary claims in trespass and nuisance, and you have no agreed schedule of condition to point at when a pre-existing crack becomes your fault.

You also inherit a problem at sale. A buyer's solicitor asking for the party wall award and being told there isn't one is a conveyancing delay at best.

Flats, leaseholds and who counts as an owner

The Act reaches further than shared houses.

Section 20 defines a party structure to include a floor partition or other structure separating parts of buildings approached by separate staircases or entrances. So the floor between two flats can be a party structure, and work to it can be notifiable.

"Owner" is defined inclusively. A freeholder qualifies, and so does a long leaseholder. A tenant on a short assured tenancy does not, which means the person you need to notify may not be the person living there.

One thing we will not assert: whether flats reached from a shared communal staircase satisfy the section 20 wording. The drafting refers to parts of buildings approached solely by separate staircases or separate entrances, and we could not find authority resolving how that applies to a typical London conversion off a common hall. If you are altering a structure between flats, that is a question for a surveyor rather than a blog.

How this plays out on real projects

The pattern is almost always calendar rather than cost. A knock-through is two days of work sitting behind a two-month notice. A basement is a section 6 notice, a schedule of condition, and quite possibly a neighbour exercising their right to require underpinning.

Which trigger applies depends on the job:

Removing a chimney breast on a party wall is section 2, named expressly in section 2(2)(g). Our guide to chimney breast removal costs and rules covers the structural side.

Cutting a beam into a party wall is section 2(2)(f). See what knocking through actually involves.

A loft conversion may trigger nothing at all. If you are only fitting rooflights and a floor, with no work to the party wall, there is no notifiable work. It becomes section 2 the moment beams bear into the wall or the wall is raised.

Replastering, rewiring, fitting shelves are not notifiable. The duty in section 3(1) is tied to exercising a section 2 right, and none of those is one.

How Beams helps

The party wall clock is the single most common reason a London renovation starts later than the homeowner expected. Two months is not long, unless you discover you needed it in week one of a build you have already booked.

So we establish which sections apply while the design is still moving, get notices served early enough that they are never the thing holding up a start date, and make sure the schedule of condition exists before anyone touches a wall. Your builder prices the work knowing what the award requires, rather than discovering it halfway through.

That is part of what a Beams project puts in writing: one agreed price, payments released against milestones, and 12 months on the workmanship.

Common questions about the Party Wall Act

Can my neighbour refuse permission?
No. The Act grants you rights and your neighbour cannot veto them. They can dissent, which triggers the surveyor process and produces an award governing how the work is done. Dissent changes the process, not the outcome.

How long does a party wall agreement take?
The notice period alone is one or two months depending on the section. Where a dispute arises, appointing surveyors and producing an award typically adds weeks on top. Treat three months from serving notice to being clear to start as a realistic planning assumption rather than a worst case.

Do I need a party wall agreement for a loft conversion?
Only if the work touches the party wall. Steels bearing into it, raising it, or exposing it all trigger section 2. A rooflight conversion that leaves the wall alone triggers nothing.

Who pays for the surveyor?
Usually the person doing the work, but it is determined by the surveyors under section 10(13) rather than fixed by the Act. There is no statutory fee scale, which is why quotes vary.

What if my neighbour ignores the notice?
Under section 5, after 14 days a dispute is deemed to have arisen and you proceed to appointing surveyors, including on their behalf if necessary. Under section 1(4), silence instead costs you the right to build on the boundary line. Check which section you served under.

Where this information comes from

The Act itself: Party Wall etc. Act 1996, sections 1, 2, 3, 5, 6, 10 and 20, as published on legislation.gov.uk

Notice periods: section 1(2) and 1(5), section 3(2), and section 6(5)

Excavation rules, plans and underpinning: sections 6(1), 6(2), 6(3), 6(4), 6(6), 6(7) and 6(8)

Deemed dissent and its opposite: section 5 and section 1(4)

Surveyors, awards, costs and appeals: sections 10(4), 10(13) and 10(17)

No enforcement procedure, and that a neighbour cannot prevent works: Ministry of Housing, Communities and Local Government explanatory booklet on the Party Wall etc. Act 1996, last substantively updated May 2016

Party structures and the definition of owner: section 20

We have not stated a position on how section 20 applies to flats off a shared communal staircase, because we could not find authority settling it.