What Is a Party Wall Agreement and When Do You Need One?
In short
A party wall agreement is the everyday name for the process under the Party Wall etc. Act 1996, where you serve notice on neighbours before work affecting a shared wall, boundary or nearby foundations. If neighbours consent, work can proceed; if they dissent, surveyors agree a party wall award setting out how the work is done.
A party wall agreement is not a single document you download and sign. It is shorthand for the process set out in the Party Wall etc. Act 1996, which applies across England and Wales. The Act exists to let you build while protecting your neighbour’s property, and in a city of terraces and semi detached houses like London, it applies to a large share of lofts, extensions and basement projects.
When the Act applies
You generally need to serve notice if you plan to:
- Work on an existing party wall, for example cutting in to take a steel beam, inserting a damp proof course, raising the wall for a mansard or loft, or removing chimney breasts attached to it.
- Build a new wall on the boundary (the line of junction), as with many side return and rear extensions.
- Excavate near a neighbour’s building, within 3 metres and deeper than their foundations, or within 6 metres in certain cases, which catches many extensions and all basements.
How the process works
- Serve notice. The building owner serves written notice on each affected neighbour. For work on a party structure, notice is at least two months before work starts. For a new wall on the boundary or excavation, it is at least one month.
- Neighbour responds. They have 14 days to consent or dissent. If they do not reply, a dispute is deemed to have arisen.
- Surveyors appointed. If there is a dispute, either one agreed surveyor acts for both owners, or each appoints their own.
- Schedule of condition. The surveyor records the condition of the neighbour’s property, with photographs, before work starts.
- Party wall award. The surveyors agree an award setting out what work is permitted, how and when, and how any damage will be made good.
The building owner normally pays the reasonable fees of both surveyors. A party wall surveyor must act impartially, whoever appoints them.
Why to start early
Notice periods and awards take time. Serving notices as soon as the design is settled, and talking to neighbours before the paperwork arrives, avoids delays to your start date and keeps relationships good.
What happens if you ignore it
Starting notifiable work without notice can lead to an injunction stopping the work, and leaves you in a weak position if the neighbour claims damage. It can also cause problems when you sell.
How we handle party wall matters on London’s Prestige projects
We identify party wall work at the design stage, put you in touch with experienced party wall surveyors, and build the notice periods into the programme so your start date is realistic. On site, we work to the award, protect neighbouring property and keep neighbours informed. See the care taken on a boundary extension at our Meadway Close project, learn about our extension service and our guide to planning permission for London extensions, then book a site visit to plan your project properly.
Common questions
Do I need a party wall agreement for a loft conversion?
Usually, on a terraced or semi detached house, because steel beams are typically set into the party wall and the wall may be raised. A surveyor can confirm what notices are needed.
How long does the party wall process take?
Notice periods are one or two months depending on the work. If neighbours consent, work can start once the notice period ends; if surveyors are appointed, the award can take several weeks more.
Who pays for the party wall surveyor?
The building owner carrying out the work normally pays the reasonable fees of their own surveyor and the neighbour's surveyor.