If your extension sits close to a neighbour's house, the Party Wall etc. Act 1996 may apply. It is separate from planning permission and building regulations, and it applies in England and Wales. The Act does not stop you building; it sets out how you tell your neighbour and how disagreements are resolved. Here is when it applies and what you need to do.
How much notice do I need to give?
2 monthsnotice for work to an existing party wall
1 monthnotice for a new wall on the boundary, or excavation near a neighbour
14 daysfor your neighbour to respond to a notice
1 yeara notice stays valid if work hasn't started
Which works need a party wall notice?
The Act covers three main types of work:
| Type of work | Examples | Minimum notice |
|---|---|---|
| Work to an existing party wall (section 2) | Cutting into a shared wall to take a beam, raising or underpinning it | 2 months |
| A new wall on or at the boundary (section 1) | Building the wall of your extension on, or right up to, the boundary line | 1 month |
| Excavation near a neighbour's building (section 6) | Digging foundations within 3m and deeper than their foundations, or within 6m and cutting a 45° line from their foundations | 1 month |
How does the party wall process work?
- Serve noticeGive your neighbour (the "adjoining owner") written notice describing the work, at least one or two months before you start, depending on the type of work.
- Your neighbour respondsThey should reply within 14 days, either consenting or not. For work to a party wall they can also serve a counter-notice within one month, asking for additional work, which you should answer within 14 days.
- If they agreeYou can go ahead once the notice period has run. Keep a record of the condition of the neighbouring property before you start.
- If they don't agreeThe Act sets out a process for resolving the dispute, which usually involves surveyors agreeing how and when the work is done.
- Start within a yearA notice lapses if the work does not begin within one year of it being served.
Talk first, then serve noticeNeighbours who hear about the plans in person before the formal notice arrives are far more likely to consent. A friendly conversation can save weeks.
Can I build my extension wall on the boundary?
You can build a new wall right up to the boundary on your own land after giving one month's notice. If you want to build a wall astride the boundary (partly on your neighbour's land), you need their consent; if they do not consent within 14 days, you must build wholly on your own land.
What happens if work starts without notice?
It can stop your buildIf work covered by the Act starts without notice, your neighbour can seek a court injunction to stop it. That can mean a stalled site, extra cost and a damaged relationship with the people next door.
Is a party wall notice the same as planning permission?
No. The Party Wall Act, planning permission and building regulations are three separate things, and an extension can need any combination of them. See do I need planning permission for an extension? and how deep extension foundations need to be, since foundation depth decides whether the 3m and 6m rules apply.
How we help: when we price an extension, we tell you whether the Party Wall Act is likely to apply, so notices can go out early and the programme does not slip while you wait for notice periods to run.
Planning a project like this?
We can visit the site, explain what your project needs and give you a clear, itemised quote.
Frequently asked questions
Is a party wall agreement the same as planning permission?
No. The Party Wall Act is separate from planning permission and building regulations. You may need all three, or only one, depending on the work.
How long does my neighbour have to reply to a party wall notice?
Your neighbour should respond within 14 days of receiving the notice.
How long is a party wall notice valid?
A notice lapses if the work does not start within one year of it being served.
What happens if I start work without serving notice?
Your neighbour can seek a court injunction to stop the work, which can delay your project and add cost.
Does the Party Wall Act apply in Wales?
Yes. The Party Wall etc. Act 1996 applies in England and Wales.
Sources and further reading
- GOV.UK: The Party Wall etc. Act 1996 explanatory booklet
- Planning Portal: Is building regulations approval needed for an extension?
This article is general guidance for England, correct when last reviewed. Rules differ in Wales and can be changed locally (for example by Article 4 directions or planning conditions), so check with your local planning authority or building control before starting work.