Party wall agreements: when you need one and what it costs

A party wall agreement is the written consent or surveyor's award you need before building work on or near a wall you share with a neighbour in England and Wales. It comes from the Party Wall etc. Act 1996, and it applies whether or not the project needs planning permission. We cover when the Act applies, the notices and their deadlines, what your neighbour can do, what surveyors charge, and the rules in Scotland and Northern Ireland.

What a party wall agreement is

A party wall agreement is not one fixed document. It follows a party wall notice you serve on your neighbour, and it ends one of two ways: your neighbour consents in writing, or surveyors draw up a party wall award that sets out the work, how and when it is done, and who pays.

The Act runs separately from planning permission and building regulations approval, and neither one replaces it. An extension built under permitted development rights, with no planning application at all, still needs notices if it touches a shared wall or digs near the neighbour's foundations.

What counts as a party wall

Most notices turn on one of four terms in the Act:

• Party wall: a wall standing astride the boundary between two owners' land, or a wall on one owner's land that separates two buildings, such as the wall between a pair of semis.
• Party fence wall: a masonry garden wall on the boundary that is not part of a building. A wooden fence is not one.
• Party structure: a wall, floor or partition separating parts of a building with separate entrances, which is how the Act reaches flats and maisonettes.
• Line of junction: the boundary line itself, where the two owners' land meets.

When you need a party wall agreement

Three kinds of work need a written notice. The type of work sets the section of the Act and the minimum notice period.

Work to an existing party wall

Section 2 lists what you may do to a wall you already share once notice has been served. The rights include:

• Cutting into the wall to take the bearing of a beam, such as a loft conversion steel
• Inserting a damp proof course
• Underpinning the wall, or extending it downwards
• Raising its height
• Demolishing and rebuilding it
• Cutting off projections, such as a chimney breast

Cutting off projections is the right that covers removing a chimney breast from a shared wall, so that job needs 2 months' notice, the same as a loft steel.

Building a new wall on the boundary

Section 1 covers a new wall at the line of junction, whether it straddles the line or sits wholly on your side of it. The notice period is 1 month. On a side return extension on a terrace, the new flank wall usually runs along the boundary, which makes it section 1 work, and its foundations are often within 3 metres of the neighbour's house as well.

The 3 metre and 6 metre rule

Under section 6 of the Act, digging near a neighbour's building needs 1 month's notice, even when you never touch a shared wall. It applies in two cases:

• The 3 metre test: you excavate within 3 metres of any part of the neighbour's building and dig deeper than the bottom of their foundations.
• The 6 metre test: you excavate within 6 metres of their building and the dig would cut a line drawn down at 45° from the bottom of their foundations.

The 45° line means the 6 metre test only catches deep digs, such as a basement or piled foundations. For a single-storey rear extension, the 3 metre test is the one to measure: if the new trench goes deeper than the neighbour's footings within 3 metres of their house, notice is due.

Work that does not need a party wall notice

Minor work to your side of a shared wall needs no notice, such as plastering, new wiring or sockets, and drilling to put up shelves or cabinets. Nor does:

• A wooden fence on the boundary, because it is not a party fence wall.
• Digging more than 3 metres from the neighbour's building, or shallower than their foundations within 3 metres, unless the dig is deep enough to meet the 6 metre test.
• Work on a wall that stands wholly on your land and does not separate your building from anyone else's.

How to serve a party wall notice

Serve a notice on every adjoining owner. That includes the freeholder and any leaseholder on a lease of more than a year, while a tenant on a year or less is not entitled to one. A mid-terrace house usually has two adjoining owners, and a house next to a building split into flats can have several.

The notice has to be in writing and give:

• Your name and address as the owner doing the work
• The address of the building where the work happens
• A description of the work
• The date you plan to start

The minimum is 1 month before the start for a boundary wall or an excavation, and 2 months for work to an existing party wall. A notice lapses if the work has not started within a year of serving it, so serve it once the design is fixed rather than at the first sketch.

What your neighbour can do after the notice

Your neighbour has 14 days to reply in writing. They can consent, or dissent and go to surveyors, and doing nothing counts as a dispute.

Within a month of your notice, a neighbour can also serve a counter-notice asking for extra work on the wall at the same time. They pay for that extra work where it benefits them.

Can a neighbour refuse a party wall agreement?

No. A neighbour who dissents sends the work to surveyors rather than stopping it. The Act gives you the right to carry out the notified work, and your neighbour can influence how and when it is done, not whether.

If your neighbour will not appoint a surveyor, you can appoint one on their behalf once 10 days have passed after you ask them in writing. The award that follows binds them the same way.

The party wall award and the surveyors

Where your neighbour does not consent, surveyors settle the terms in a party wall award, and you cannot act as your own surveyor. Both owners can agree on one surveyor, or each appoints their own. Two surveyors pick a third, who decides anything they cannot agree on.

The award sets out the work, how and when it is done, and who pays for what. Surveyors who are chartered members of RICS carry MRICS or FRICS after their name.

The schedule of condition

The Act does not always require a schedule of condition, a dated record with photographs of the neighbour's side of the wall before work starts. It is still worth having, because it is the evidence that settles whether a later crack came from your work. You must fix or pay for any damage your work causes, and avoid unnecessary inconvenience to the neighbour while it runs.

Access, security and appeals

The Act lets your surveyor and builders into the neighbour's property during usual working hours to carry out the notified work, with 14 days' notice except in an emergency. Refusing that access can be prosecuted in the magistrates' court. Your neighbour can also ask you to put up security for expenses before work starts.

An award binds both owners. Either side can appeal to the county court within 14 days of the award being served, and after that it stands.

What a party wall agreement costs

Written consent costs nothing. Everything else is surveyors' time, at around £150 to £200 an hour, and the job decides how many hours an award takes. A boundary wall or an extension's foundations usually sit at the lower end, and steels cut into a party wall at the upper end.

Who pays the party wall surveyor

The owner doing the work normally pays every surveyor, including the neighbour's own surveyor where the work is for the owner's benefit alone. So one agreed surveyor means one fee, and two surveyors mean you pay both.

The neighbour pays a share in three cases: where the work puts right a defect or lack of repair in the wall, where they asked for extra work by counter-notice and it benefits them, and where they act unreasonably by making excessive demands.

On a terrace or semi, loft steels usually bear into the party wall, so a loft can need an award on each side, and £1,200 to £3,000 per agreement belongs in the cost of a loft conversion from the first quote.

Common projects that need a party wall notice

These are the everyday jobs that bring the Act in, with the notice each one usually needs.

A project that combines these, such as a loft and a rear extension on a semi, needs a notice for each type of work, and the 2 month notice sets the earliest start.

How long the party wall process takes

The notice period is the minimum wait. With consent in writing, work can start once it has run. With surveyors involved, the award has to be agreed first, and that can take longer than the notice itself.

We would serve 3 to 4 months ahead of the planned start on any job needing a party structure notice. The notice holds for a year, and the extra weeks leave room for a dissent without moving the builder's start date.

Starting work without a party wall agreement

If you start notifiable work without serving notice, your neighbour can go to court for an injunction to stop it. You also stay liable for any damage the work causes, with no schedule of condition to show the state of the wall beforehand.

The same route runs the other way. If a neighbour starts notifiable work next door without serving you notice, ask them in writing to stop and serve one, and an injunction is available if they carry on.

Party walls in Wales, Scotland and Northern Ireland

Wales follows the same Act as England, with the same notices, periods and awards. The Act does not apply in Scotland or Northern Ireland, so there is no party wall notice to serve in either.

In Scotland, flats come under section 9 of the Tenements (Scotland) Act 2004. No owner or occupier may do anything that would, or would be reasonably likely to, materially impair the support or shelter of any part of the building, or its natural light, and any owner directly affected can enforce that. Taking out a structural wall in a tenement flat is a question for the neighbours as well as for the building warrant.

Northern Ireland runs its own building control system, and a house there or in Scotland has no party wall notice to serve. With no procedure to follow, we would agree the work with the neighbour in writing and photograph their side of the wall, with their permission, before anything starts.