Do I Need a Party Wall Notice for an Extension?
If you are planning a rear, side or wraparound extension, you may need to serve a Party Wall Notice before work begins. However, an extension does not automatically fall within the Party Wall etc. Act 1996.
Whether notice is required depends mainly on where the new walls will be built, whether you will carry out work to an existing party wall or structure, and the depth and position of the proposed foundations in relation to neighbouring buildings.
For many extensions, more than one section of the Act can apply.
The short answer
You may need to serve a Party Wall Notice for an extension if your work involves:
- building a new wall at or astride the boundary with your neighbour;
- cutting into, raising, demolishing or otherwise carrying out certain work to an existing party wall or party structure; or
- excavating close to a neighbouring building and to a sufficient depth for section 6 of the Party Wall etc. Act 1996 to apply.
The Act applies in England and Wales and is separate from planning permission and Building Regulations approval.
What is the Party Wall etc. Act 1996?
The Party Wall etc. Act 1996 provides a statutory procedure for certain building works affecting, or taking place close to, neighbouring properties.
Despite its name, it does not only apply to work directly to a shared wall. It can also apply to new walls at a boundary and excavation carried out wholly within your own property.
The purpose of the Act is to allow a Building Owner to carry out qualifying work while providing certain protections to an Adjoining Owner whose property could be affected.
For a typical domestic extension, there are three areas that need to be considered.
1. Are you building a new wall at the boundary?
Section 1 of the Act concerns building new walls on the “line of junction”. In simple terms, this is usually the boundary between two properties.
If you propose to build a new wall astride the boundary, you must serve notice on the Adjoining Owner. The neighbour does not have to agree to a new wall being built astride the boundary.
If they do not give written consent, the wall must normally be built wholly on your own land.
A notice can also be required where a new wall is to be constructed wholly on your own land but directly at the line of junction.
The statutory notice period for this type of work is at least one month.
This is particularly relevant to side and rear extensions where the designer intends to maximise the available width by positioning the new wall directly against the boundary.
2. Will the extension involve work to an existing party wall?
Section 2 of the Act provides rights to carry out various works to existing party walls and party structures.
Common examples associated with domestic extensions and alterations include:
- cutting pockets into a party wall to support structural steel beams;
- raising the height of an existing party wall;
- demolishing and rebuilding a defective party wall;
- cutting away chimney breasts or other projections connected with a party wall; and
- carrying out certain structural works affecting a shared wall or structure.
A Party Structure Notice is normally required at least two months before the proposed work begins.
This is particularly common where an extension forms part of a wider refurbishment project or where steelwork is being installed between existing party walls.
3. Are the new foundations close to your neighbour’s building?
This is one of the most commonly misunderstood parts of the Party Wall etc. Act.
Simply being within three metres of a neighbouring property does not automatically mean that a Party Wall Notice is required.
Under section 6(1), notice is required where the proposed excavation is within three metres of a neighbouring building or structure and the excavation will extend below the bottom of that building’s existing foundations.
There is also a separate six-metre test under section 6(2), which considers the depth of the proposed excavation against a 45-degree plane drawn from the bottom of the neighbouring foundations towards the proposed excavation.
This means the actual foundation depths matter.
For example, if both properties have similar traditional strip foundations at approximately the same depth, a new extension may be within three metres without section 6 necessarily being triggered.
Conversely, deep trench-fill foundations, piled foundations or a basement excavation can trigger the Act even where the work is considerably further from the adjoining building.
The plans and sections accompanying a section 6 notice must show the location and depth of the proposed excavation and the location of the proposed building or structure.
Does an extension always require a Party Wall Surveyor?
No.
There is an important distinction between needing to serve a notice and needing Party Wall Surveyors to make an Award.
A Building Owner can serve a valid Party Wall Notice directly, although many owners instruct a surveyor to review the drawings and serve the notices on their behalf.
If the Adjoining Owner receives a section 2 or section 6 notice and gives written consent, there may be no statutory dispute requiring surveyors to be appointed.
If they dissent, or fail to respond to certain notices within 14 days, a dispute arises under the Act and the section 10 surveyor procedure then applies.
The owners may agree on one Agreed Surveyor, or they can each appoint their own surveyor.
What if my neighbour is happy with the extension?
A good relationship with your neighbour is helpful, but it does not remove the requirement to serve notice where the Act applies.
Where notice is required, it should still be properly served.
Your neighbour can then consent in writing. Depending on the circumstances, it may also be sensible to prepare a photographic Schedule of Condition of the adjoining property before work begins.
A Schedule of Condition records the condition of relevant parts of the neighbouring property before construction starts. This can provide useful evidence for both owners if allegations of damage arise later.
RICS guidance identifies a Schedule of Condition as something that will usually be of value even where an Adjoining Owner consents to the work.
Is a Party Wall Notice the same as planning permission?
No.
Planning permission, Building Regulations and the Party Wall etc. Act deal with different matters.
Obtaining planning permission does not remove your obligations under the Party Wall etc. Act.
Likewise, your neighbour cannot normally use the Party Wall process simply to prevent development because they dislike the design or objected to the planning application. The Party Wall process concerns the rights, protections and manner in which works covered by the Act are carried out.
You should therefore consider Party Wall requirements separately and ideally at an early stage in the design process.
When should I get Party Wall advice?
The best time is before construction drawings and the programme are finalised.
Early advice allows a Party Wall Surveyor to review matters such as:
- the proposed position of new walls;
- foundation type and depth;
- the position and likely depth of neighbouring foundations;
- structural steel connections;
- demolition affecting existing shared structures;
- access requirements; and
- whether one or several different notices are required.
This can help avoid invalid notices, unnecessary delay and last-minute changes to the construction programme.
Section 1 and section 6 notices generally require at least one month’s notice, while works to existing party structures under section 2 generally require at least two months’ notice. Notices are normally valid for 12 months, subject to the requirements of the Act.
You should therefore avoid leaving the Party Wall process until your contractor is ready to start.
Frequently asked questions
Do permitted development extensions need a Party Wall Notice?
They can.
Permitted development relates to planning law. The Party Wall etc. Act is separate.
An extension that does not require a planning application may still require Party Wall Notices if its walls, foundations or associated structural works fall within the Act.
Does an extension within three metres always require notice?
No.
For section 6(1) to apply, the excavation must be within three metres and extend deeper than the bottom of the neighbouring building’s foundations.
Both distance and depth must therefore be considered.
Can my neighbour stop my extension by refusing a Party Wall Notice?
A dissent to a Party Wall Notice does not normally give an Adjoining Owner a veto over works that the Building Owner is entitled to undertake.
Instead, the Act provides a dispute-resolution process involving an Agreed Surveyor or separate surveyors who can determine matters falling within their statutory jurisdiction.
Can I start before the notice period expires?
The normal notice periods must be observed unless the relevant Adjoining Owner agrees in writing to an earlier start.
What happens if I build without serving notice?
The Act itself does not contain a conventional enforcement procedure for failing to serve notice.
However, an Adjoining Owner may seek legal remedies, including potentially applying to the court for an injunction to stop works. Proceeding without complying with the Act can also make later disputes over damage substantially more difficult.
Party Wall advice for extensions in Essex and the South East
PJF Surveying LLP provides Party Wall advice to Building Owners and Adjoining Owners throughout Essex and the South East.
We can review your architectural and structural drawings, advise whether the Party Wall etc. Act 1996 applies, prepare and serve the required notices, prepare Schedules of Condition and act as Building Owner’s Surveyor, Adjoining Owner’s Surveyor or Agreed Surveyor where a dispute arises.
Obtaining advice early can help ensure that the correct procedure is followed before your building programme begins.
Contact PJF Surveying to discuss your proposed extension and Party Wall requirements.
Author: Peter Furness BSc (Hons), AssocRICS, MCIOB, MFPWS
PJF Surveying LLP – RICS regulated surveying practice
Last reviewed: October 2026