Party Wall Rules for Home Extensions
A home extension will often fall under the Party Wall etc. Act 1996. It applies if you build on or astride the boundary, cut into an existing party wall, or dig foundations near a neighbouring building. An extension set well back from the boundary with shallow foundations may not need any notice.
Three ways an extension is caught
Extensions can engage each of the three kinds of work covered by the Act.
- Section 1: building a new wall on the line of junction between the two properties.
- Section 2: cutting into, raising, or altering an existing party wall, for example to tie in a new side wall or insert a beam.
- Section 6: excavating within 3 metres of a neighbouring building where you go deeper than its foundations, or within 6 metres where the excavation cuts a line at 45 degrees down from the bottom of its foundations.
Side returns and rear extensions
A rear extension on a semi-detached or terraced house usually sits next to the neighbour's boundary. Even if you build wholly on your own land, the foundations may fall within the excavation distances. Wall tie-ins to the existing party wall also count.
A wall built right up to the boundary but wholly on your own land is covered by a separate notice type, and the neighbour's consent to build on their land is not required.
Notice periods
Allow at least two months for work to an existing party wall, and at least one month for a new wall on the line of junction or for excavation. Notices should describe the work, and excavation notices need plans and sections.
What happens next
The neighbour has 14 days to respond. Either they consent, dissent, or say nothing, in which case a dispute is treated as having arisen. Surveyors then make an award covering how and when the work is done, and a schedule of condition of the neighbour's property.
Planning is separate
Planning permission and building regulations approval do not remove the need for party wall notices. Deal with all three early so your builder is not held up.
Frequently asked questions
Do I need a notice for a single-storey extension?
Possibly. It depends on whether you touch the party wall or dig near the neighbour's foundations. A surveyor can check your drawings.
Can my neighbour stop the extension?
No. The Act does not give a right of veto. It regulates how the work is done and protects the neighbour's property.
What if I have already started?
Stop and take advice. Notices can sometimes be served late, but risk and cost are higher.
Related guides
- Understanding Section 1 of the Party Wall Act: New Walls on Junction Lines
- Understanding Section 6 of the Party Wall Act: Excavation Within 3 or 6 Metres
- Party Wall Rules for Loft Conversions
- Excavations and Foundational Underpinning: Party Wall Rules Explained
Last updated: . This page is general information about the Party Wall etc. Act 1996 (England and Wales). It is not legal advice. Every property and dispute is different, so take advice from a party wall surveyor or a solicitor before you act.