Key Takeaways
- The Party Wall etc. Act 1996 applies when you work on a shared wall, build on the boundary, or excavate near a neighbour's foundations.
- Notice periods are two months for work to an existing party wall and one month for a new boundary wall or nearby excavation (gov.uk, 2026).
- Your neighbour has 14 days to reply. Saying nothing counts as dissent.
- If they dissent, surveyors produce a party wall award, typically £900 to £2,700 with one agreed surveyor (HomeOwners Alliance, 2026).
- Common triggers include loft conversions, extensions, basements and RSJ installations into a party wall.
- Starting without notice risks a court injunction that stops the job dead, so plan for it early.
In London's tightly packed terraces and semis, many renovation projects touch a shared wall or boundary, which brings the Party Wall Act into play. Handled early and correctly, it is straightforward. Here is what you need to know.
What is the Party Wall Act?
The Party Wall etc. Act 1996 gives you a legal right to carry out certain work to shared walls and boundaries, and gives your neighbour a right to be told first and protected while it happens. It is a private process between two owners that runs alongside any planning application or Building Regulations approval, and none of the three substitutes for the others.
A "party wall" in the Act's sense is wider than most people expect. It covers the wall between two terraced houses, a garden wall astride the boundary, and the floor structure separating one flat from another. It also catches work nowhere near a shared wall, because deep excavation close to a neighbouring building is covered too.
Which works trigger the Act?
Three sections catch three different types of work. Section 1 covers a new wall on or up to the boundary. Section 2 covers work to an existing shared structure, such as cutting in a steel beam, underpinning, raising it or removing chimney breasts off it. Section 6 covers excavation within three metres of a neighbouring building deeper than its foundations, or within six metres and below a line drawn down at 45 degrees from those foundations.
| Work | Section | Notice type | Minimum notice |
|---|---|---|---|
| New garden or flank wall on or up to the boundary | Section 1 | Line of junction notice | 1 month |
| Cutting into a party wall to seat an RSJ | Section 2 | Party structure notice | 2 months |
| Removing a chimney breast off a party wall | Section 2 | Party structure notice | 2 months |
| Underpinning or raising a party wall | Section 2 | Party structure notice | 2 months |
| Loft steels bearing on the party wall | Section 2 | Party structure notice | 2 months |
| Foundations within 3m of next door, deeper than its footings | Section 6 | Notice of adjacent excavation | 1 month |
| Basement dig within 6m, below the 45 degree line | Section 6 | Notice of adjacent excavation | 1 month |
One project often triggers more than one section. A rear extension with a new flank wall on the boundary and foundations tight to next door needs both a line of junction notice and a notice of adjacent excavation, so serve them together and work to the longest period. This catches most London loft conversions, extensions, basements and structural works.
What must a party wall notice say?
A valid notice is written, served on every affected owner, and served one or two months before you intend to start, depending on the section. It must contain:
- Your full name and address, naming every joint owner
- The address of the property where the work will be done
- A full description of what you propose to do, and the date you intend to start
- For excavation notices, plans and sections showing the position and depth of the dig
Notice stays valid for one year, so serve it once the design is settled rather than eighteen months early. Work out who the adjoining owners are first: a mid-terrace extension can have two, and in a converted flat the freeholder and leaseholder are separate owners who each need notice.
What happens when a neighbour consents or dissents?
Your neighbour has 14 days to reply, and there are only two outcomes.
- Consent. They agree in writing, you may proceed, and there is no award and no surveyor fee. Take your own photographic schedule of condition anyway, because consent does not remove your liability for damage.
- Dissent. A dispute is deemed to have arisen and surveyors take over. Silence counts: with no written reply within 14 days to a section 2 or section 6 notice, the Act treats it as a dispute.
Dissenting is not a veto. It moves the question to surveyors, who decide how and when the work is done, not whether it happens.
What is a party wall award?
A party wall award is a binding document written by the appointed surveyors setting out exactly how and when the work may be done. It usually:
- Describes the permitted work, and when and how it may be carried out, including working hours and access
- Records the condition of the neighbouring property beforehand in a photographic schedule of condition
- Specifies any extra protective or remedial work required
- Gives the surveyors access to inspect, and decides who pays their fees
Either owner can appeal to the county court within 14 days of service. Appeals are rare and expensive, and the award binds both parties meanwhile.
Agreed surveyor or two surveyors?
One agreed surveyor acting impartially for both owners is cheaper and faster, and it is the right choice on most straightforward domestic jobs. If your neighbour will not accept that, each side appoints its own, and those two select a third surveyor in advance to settle anything they cannot agree.
Two surveyors earn their cost where the risk is high: a basement dig, underpinning, deep foundations beside a period building, or a hostile neighbour. Once appointed, a surveyor cannot be dismissed by either owner, so choose carefully.
What does the party wall process cost?
If your neighbour consents in writing there may be no surveyor cost at all. If they dissent, expect £900 to £2,700 for a single agreed surveyor, and £1,800 to £5,400 where each side appoints its own.
| Scenario | Typical cost | Who pays |
|---|---|---|
| Neighbour consents in writing | £0 to £250 for drafting the notices | Building owner |
| One agreed surveyor, straightforward job | £900 to £2,700 | Building owner |
| Two surveyors, one each side | £1,800 to £5,400 | Building owner, usually both fees |
| Surveyor hourly rate, London and the South East | £150 to £300 per hour | Building owner |
| Third surveyor referral | Charged hourly on top | Decided in the award |
The building owner, meaning you, normally pays all reasonable fees including your neighbour's surveyor. Costs also multiply with the number of adjoining owners, so a mid-terrace project where two neighbours both dissent can double the figures above.
What if you start work without serving notice?
Your neighbour can apply to court for an injunction that stops the work, and you can be ordered to put things right at your own expense. The wider damage:
- The job halts while trades stand idle and still expect paying.
- You lose the Act's protections, so you have no statutory right to cut into the wall or place foundations, and may be trespassing.
- Any damage claim gets harder, because there is no agreed schedule of condition to prove which cracks were already there.
- The gap resurfaces on sale, because a buyer's solicitor will ask about party wall agreements.
Serving late is not a fix. If work has begun, most surveyors will tell you to stop, serve properly and wait out the notice period.
Which London projects usually need it?
In London terraces and semis, most structural projects trigger the Act, because the party wall carries floors and roof for both houses at once. The usual list:
- RSJ installation into a party wall for an open-plan layout
- Chimney breast removal, where the stack is shared
- Basement conversions, underpinning, and loft steels bearing on the party wall
- Rear and side extensions with foundations close to the boundary
Party wall consent, planning permission and Building Regulations approval run on three separate timelines, and the notice period is the one people forget to allow for. We coordinate the process as part of the programme so it does not hold up your build. For advice, contact us or call 07472 424 226.