When planning a house extension, one legal step that is often missed is the Party Wall Notice. If your extension involves a shared wall, building on the boundary or digging foundations close to a neighbouring property, the Party Wall etc. Act 1996 may require you to notify your neighbour formally before work begins.
This guide explains how to tell whether your extension is covered, how the notice process works and what happens if your neighbour does not consent. The Act applies in England and Wales.
What Is a Party Wall Notice?
A Party Wall Notice is a formal written notice that a building owner (the person carrying out the work) serves on an adjoining owner (the neighbour) before starting certain types of work covered by the Party Wall etc. Act 1996.
The Act allows the building owner to carry out notifiable work while protecting the neighbouring property and providing a route to resolve disagreements through surveyors rather than the courts. A valid notice should include:
- the name and address of the building owner
- a clear description of the proposed works
- the date on which the works are intended to start
- drawings showing the position and depth of foundations, where excavation is involved
The term adjoining owner can include more than one party. Freeholders and leaseholders with a lease of more than a year may all need to be served, which is common where a neighbouring house has been converted into flats.
When Is a Party Wall Notice Required for an Extension?
Three types of work under the Act are most relevant to house extensions. Many projects involve more than one, so more than one notice may be needed.
Building on or Near the Boundary
If you plan to build a new wall on or astride the boundary, known in the Act as the line of junction, you must serve a line of junction notice under section 1 at least one month before work starts. This often applies to side extensions on semi-detached houses and rear extensions that run along the boundary. A wall can only be built astride the boundary with your neighbour’s written consent. Without it, the wall must be built wholly on your own land.
Work Affecting a Shared Party Wall
Work to an existing party wall requires a party structure notice under section 2, served at least two months before work starts. Common examples linked to extensions and loft conversions include:
- cutting into a party wall to insert steel beams, often for loft conversions or knocking through to a rear extension
- raising the height of a party wall or extending it upwards
- underpinning or thickening a party wall
- cutting in a damp proof course or lead flashing
- removing chimney breasts attached to a party wall
Excavation Near an Adjoining Property
An excavation notice under section 6 is required if:
- you will excavate within 3 metres of a neighbouring building or structure and go deeper than the bottom of its foundations, or
- you will excavate within 6 metres of a neighbouring building or structure and the excavation will cut a line drawn downwards at 45 degrees from the bottom of its foundations
An excavation notice must be served at least one month before work starts. This is the section that applies to many rear extensions, because new foundations are often deeper than those of older neighbouring houses, particularly on clay soils or near trees.
Common House Extension Projects and Party Wall Notice Requirements
| Extension Project | Is a Party Wall Notice Likely to Be Required?* |
| Rear extension involving excavation near a neighbouring property | Often required, depending on the location and depth of excavation |
| Side extension built close to the boundary | May be required, depending on the proposed works |
| Work directly affecting a shared party wall | Usually required |
| Loft conversion with steel beams inserted into a party wall | Usually required |
| Internal alterations with no impact on the party wall | Not usually required under the Act |
| Detached extension well away from neighbouring boundaries | Often not required, though individual circumstances should be assessed |
*Whether a Party Wall Notice is required depends on the specific nature and location of the proposed works. Homeowners should obtain professional advice if they are unsure whether the Party Wall etc. Act 1996 applies.
When Is a Party Wall Notice Not Usually Required?
Internal Alterations
Work inside your home that does not affect the party wall, such as moving non-structural partitions or fitting a new kitchen, is not usually covered by the Act. Internal structural work that involves cutting into the party wall, such as supporting a beam on it, is covered.
Work Well Away from the Boundary
A detached extension or garden building positioned well away from neighbouring structures, with foundations outside the 3 metre and 6 metre zones, will often not need a notice. These distances are measured from the neighbour’s building or structure, not from the boundary line, so they are worth checking carefully.
Minor Non-Notifiable Works
Some minor work to a party wall is generally treated as falling outside the Act, including:
- drilling to fix shelves, wall cupboards or kitchen units
- drilling to add or replace recessed wiring and sockets
- replastering
How the Party Wall Notice Process Works
Serving the Notice
Notices must be in writing and can be delivered by hand or by post. Email is only acceptable where the adjoining owner has agreed in advance to receive notices that way. Speaking to your neighbour first often makes the formal process smoother.
Notice Periods
| Type of Notice | Section of the Act | Minimum Notice Period |
| Line of junction notice (new wall on or at the boundary) | Section 1 | One month |
| Party structure notice (work to an existing party wall) | Section 2 | Two months |
| Excavation notice (foundations near a neighbouring structure) | Section 6 | One month |
Work can start sooner if the adjoining owner agrees in writing. A party structure notice also lapses if work has not begun within 12 months of it being served.
Neighbour Responses
Once a party structure or excavation notice has been served, the adjoining owner can:
- consent in writing, allowing the work to go ahead as described
- dissent, which means a dispute is treated as having arisen and surveyors are appointed
- not respond, in which case a dispute is treated as having arisen after 14 days
Dissent is not the same as objecting to your extension. It simply means your neighbour wants the work to be governed by a Party Wall Award.
Appointing Surveyors
When a dispute arises, the owners either agree on one surveyor to act for both or each appoint their own. If the adjoining owner does not appoint a surveyor within 10 days of a further written request, the building owner can appoint one on their behalf.
Party Wall Award
The surveyor or surveyors then prepare a Party Wall Award, sometimes called a Party Wall agreement. This legally binding document typically sets out:
- the work to be carried out and how it will be done
- working hours and any conditions to protect the neighbouring property
- a schedule of condition recording the state of the neighbouring property before work starts
- access arrangements and who pays the surveyors’ fees
Either owner can appeal an award to the county court within 14 days of it being served.
What Happens If Your Neighbour Does Not Consent?
A lack of consent does not normally stop your extension. The Act is designed to manage how notifiable work is carried out rather than to give neighbours the power to block it.
Dissent and Dispute Resolution
When a neighbour dissents or does not respond, the dispute is resolved by the surveyors through the Party Wall Award. Surveyors have a statutory duty to act impartially, even when appointed by one owner.
Agreed Surveyor
An agreed surveyor acts for both owners. This is usually quicker and less costly because only one surveyor is involved.
Separate Surveyors
Each owner can appoint their own surveyor. The two surveyors select a third surveyor, who is only called upon if they cannot agree. The building owner normally pays the reasonable fees of both surveyors, as the work is being carried out for their benefit.
Common Mistakes Homeowners Make
Starting Work Too Early
Starting notifiable work before the notice period ends, or before an award is in place, can lead to your neighbour seeking a court injunction.
Assuming Planning Permission Covers Party Wall Matters
Planning permission, permitted development rights and Building Regulations approval are separate from the Party Wall etc. Act 1996. Council approval does not remove the need to serve notice.
Serving an Incorrect Notice
A notice with missing information, under the wrong section of the Act or not served on every owner of the neighbouring property may be invalid. Work carried out under an invalid notice may not have the protection of the Act.
Delaying Professional Advice
Leaving Party Wall matters until your builder is ready to start is a common cause of delay. Allow for two months’ notice for party structure work, plus time to agree an award.
When Should You Contact a Party Wall Surveyor?
Before Finalising Plans
A Party Wall Surveyor can review your drawings and confirm which sections of the Act apply, so foundation depths and wall positions can be considered at design stage.
Before Serving Notice
Professional preparation helps make sure each notice is correctly drafted, contains the right information and is served on every adjoining owner.
If a Dispute Arises
If your neighbour dissents or does not respond, a surveyor can act on your behalf, or as an agreed surveyor, and prepare the award so work can go ahead.
Frequently Asked Questions
Do I need a Party Wall Notice for a house extension?
You will need one if your extension involves building on the boundary, working on a shared party wall, or excavating near a neighbouring structure to the depths set out in the Party Wall etc. Act 1996. Many rear and side extensions fall into at least one of these categories.
How much notice must I give my neighbour?
You must give at least one month’s notice for a new wall on the boundary and for excavation near a neighbouring structure, and at least two months’ notice for work to an existing party wall. Your neighbour can agree in writing to the work starting sooner.
What happens if my neighbour refuses to consent?
If your neighbour dissents, a dispute is treated as having arisen under the Act. This does not normally stop the work. Instead, surveyors are appointed to prepare a Party Wall Award that sets out how and when the work can be carried out.
Does planning permission replace a Party Wall Notice?
No. Planning permission, permitted development rights and Building Regulations approval are separate legal requirements. The Party Wall etc. Act 1996 deals specifically with work affecting shared walls, boundaries and neighbouring foundations, so you may still need to serve notice even if your extension has full planning approval.
Can I start building before the notice period ends?
Only if your neighbour agrees in writing. Otherwise, you must wait for the notice period to end and, where a dispute has arisen, for a Party Wall Award to be in place. Starting notifiable work early can lead to a court injunction that halts work on site.
What is a Party Wall Award?
A Party Wall Award is a legally binding document prepared by the appointed surveyor or surveyors. It sets out the work to be carried out, how and when it can be done, a schedule of condition of the neighbouring property, any access arrangements and who pays the surveyors’ fees.
Who pays the Party Wall Surveyor’s fees?
In most cases, the building owner pays the reasonable fees of all surveyors involved, because the work is being carried out for their benefit. The Party Wall Award confirms how costs are to be paid, and the position can differ where the adjoining owner asks for additional work for their own benefit.
Do rear extensions require a Party Wall Notice?
Many do. A rear extension often needs an excavation notice because its foundations are within 3 metres of the neighbouring house and deeper than that property’s foundations. Further notices may be needed if the extension is built on the boundary or involves cutting into a party wall.
What happens if I don’t serve a Party Wall Notice?
Failing to serve notice is not a criminal offence, but your neighbour could apply to the court for an injunction to stop the work. Without a schedule of condition, you may also find it harder to defend claims that your work has damaged the neighbouring property.
When should I contact a Party Wall Surveyor?
Ideally while your plans are being drawn up, and at least two to three months before building work starts. Early advice allows the correct notices to be served on time and leaves room for an award to be agreed without delaying your builder.
Conclusion
A Party Wall Notice is likely to be required for your house extension if the work involves building on the boundary, altering a shared party wall or excavating near a neighbouring property. Rear extensions, side extensions and loft conversions commonly fall within the Party Wall etc. Act 1996.
Serving the correct notices in good time, keeping your neighbour informed and taking professional advice before construction starts will help you meet your legal obligations and avoid delays.
Planning a house extension? Speak to our experienced Party Wall Surveyors before work begins. We can confirm whether the Act applies to your project, prepare and serve Party Wall Notices, act as agreed surveyor or building owner’s surveyor, and prepare Party Wall Awards to keep your extension on track. Contact our team to discuss your plans.