You need to follow the party wall process if your extension involves building on or astride the boundary, working on a shared wall, or digging foundations close to a neighbour's foundations. In those cases you serve written notice on the affected neighbours before work begins. If they consent in writing, no surveyor is needed. If they dissent or do not reply, surveyors are appointed to agree a party wall award that sets out how the work will be carried out. This guide explains the process in general terms; a party wall surveyor can advise on your specific project.
What the Party Wall etc. Act 1996 covers
The Act applies across England and Wales and sets out a fair procedure for building work that affects a shared wall or boundary. It does not decide whether you can build; that is a matter for planning and Building Regulations. Instead, it protects both owners by making sure the neighbour is told in advance and that any damage or disagreement can be dealt with in an agreed way.
For a typical house extension, three situations bring the Act into play.
- Work to an existing party wall, such as cutting in to insert a steel beam, raising the wall or underpinning it.
- Building a new wall on or astride the boundary line, for example where an extension wall sits right on the line between two gardens.
- Excavating near a neighbour's building, usually within three metres of their structure and deeper than its foundations, or within six metres in some cases depending on depth.
The notice types, in plain English
Each situation has its own notice. A party structure notice is used for work to an existing shared wall and generally needs to be served at least two months before that work starts. A line of junction notice covers a new wall on or at the boundary and usually needs at least one month. A notice of adjacent excavation covers digging near a neighbour's foundations and also usually needs at least one month.
A notice should name the owners, describe the proposed work, give the address and say when you intend to start. Drawings are often included with excavation notices. Owners can serve notices themselves, though many people ask a surveyor to prepare them so the details are right. Remember that the people to notify are the owners, which can include a landlord as well as the tenant living next door.
How neighbours can respond
Once notice is served, the neighbour has fourteen days to reply. They can consent in writing, in which case the work can go ahead when the notice period ends, ideally with a schedule of condition recording the state of their property first. Alternatively they can dissent, which triggers the dispute procedure. If they do not reply within fourteen days, a dispute is treated as having arisen.
In a dispute, the owners either agree on a single surveyor to act for both of them, or each appoints their own. The surveyors' job is to be impartial and to produce a party wall award. The building owner, meaning the person carrying out the work, normally pays the reasonable surveyors' fees.
The award, timings and planning them into the build
A party wall award sets out what work will be done, how and when it will be done, and usually includes a record of the neighbouring property's condition beforehand. It can include drawings and conditions such as working hours or protective measures. Either owner can appeal an award in court within a short period, though that is uncommon.
The main practical point is timing. Notices, responses and awards all take time, so it is worth starting the process once your drawings show where walls and foundations will go, rather than waiting until a start date is fixed. Your builder needs to know the outcome before groundwork begins, because an award can affect foundation design or the order of work along the boundary.
Talking to neighbours early
A friendly conversation before any notice arrives makes a real difference. Show your neighbours the plans, explain which parts are near their wall and give them a sense of when work might happen. Many people are happy to consent once they understand what is involved, especially when a schedule of condition gives them reassurance. A formal letter landing without warning is far more likely to prompt a dissent.
It also helps to talk about practical matters such as deliveries, skips, access and working hours. These are not part of the Act, but they shape how the project feels for the people next door.
How it fits with planning and Building Regulations
Party wall matters run alongside planning and Building Regulations but are entirely separate. Permission from the council does not remove the need to serve notice, and a neighbour's consent under the Act does not grant planning permission. Our guide to extension planning permission explains the planning side, and the house extension cost guide lists surveyors' fees among the costs to budget for.
Superior Build & Landscape builds home extensions across Northamptonshire. We are builders, not party wall surveyors, so for advice on your specific notice or award we recommend speaking to a party wall surveyor. George is happy to explain how the build side works once your approvals are in place.
Frequently asked questions
Is a party wall agreement the same as planning permission?
No. Planning permission comes from the council and deals with whether the extension can be built. The party wall process deals with how work affecting a shared wall or boundary is carried out between neighbours.
Do I need one for a single storey rear extension?
Often, yes, if the extension is built on the boundary, cuts into a shared wall or has foundations close to and deeper than a neighbour's. If none of those apply, the Act may not be involved.
What happens if my neighbour does not reply?
If there is no reply within fourteen days of notice being served, a dispute is treated as having arisen and surveyors are appointed to prepare an award.
Who pays for the party wall surveyor?
The building owner, meaning the person carrying out the work, normally pays the reasonable surveyors' fees, including those of a surveyor appointed by the neighbour.
How early should I serve notice?
At least the minimum notice period before the relevant work, which is generally two months for work to a party wall and one month for excavation or a new boundary wall. Serving earlier leaves time for any award.