Building on the Boundary: When Do You Need a Party Wall Notice?
Building an extension, garage or new garden wall close to your neighbour’s boundary can raise questions about the Party Wall etc. Act 1996 (Do I need a Party Wall Notice for an extension?).
Many homeowners assume that the Act only applies when work is being carried out to an existing shared wall. However, it can also apply when constructing a completely new wall at the boundary between two properties.
Section 1 of the Act deals specifically with building new walls on what is known as the Line of Junction.
Importantly, the rules are different depending on whether the proposed wall will stand entirely on your own land or partly on your neighbour’s land.
Understanding these differences before construction begins can help avoid unnecessary delays, additional expense and disagreements with neighbouring property owners.
The short answer
If you intend to construct a new wall directly up to the boundary between your property and your neighbour’s property, you will normally need to serve a Line of Junction Notice under Section 1 of the Party Wall etc. Act 1996, provided the circumstances fall within that section.
The notice must be served at least one month before the proposed work begins.
There are two principal situations:
Building wholly on your own land: You can generally construct a new wall entirely within your boundary after serving the appropriate notice and allowing the statutory notice period to expire. Your neighbour’s consent is not ordinarily required simply for the wall to be built on your land.
Building astride the boundary: If you want the new wall to stand partly on your neighbour’s land, their written consent is required. Without that consent, the Act does not give you the right to construct the wall astride the boundary.
The precise position of the boundary, the proposed wall construction and its foundations must all be considered.
What is the Line of Junction?
The Line of Junction is the legal boundary separating land belonging to different owners.
For example, consider two neighbouring houses with gardens separated by timber fencing.
The legal boundary may run along the fence, although the fence itself does not necessarily identify the exact boundary position.
If one homeowner proposes to construct a new brick wall directly up to that boundary, Section 1 may apply.
The legislation deals with situations where adjoining land is not already built upon at the Line of Junction, or where there is only a boundary wall that is not a party fence wall or the external wall of a building.
This distinction matters because the statutory provisions concerning an existing party wall are different from those dealing with the construction of a new wall.
When does Section 1 of the Party Wall Act apply?
Section 1 commonly becomes relevant where a homeowner intends to construct a new wall directly at the boundary.
Examples include:
- The external wall of a new side extension.
- A new garage constructed against the boundary.
- A brick or blockwork garden wall.
- A new wall forming part of a garden room or outbuilding.
- A new external wall forming part of a larger residential development.
However, the Act does not automatically apply simply because building work is taking place somewhere near a boundary.
The proposed wall must fall within the circumstances described by Section 1.
A wall deliberately set back from the boundary may fall outside Section 1, although other parts of the Act could still apply to the project.
This is why the actual construction drawings should be reviewed rather than relying solely on a general description of the proposed building work.
Building a new wall wholly on your own land
Section 1(5) deals with constructing a new wall at the Line of Junction where the wall itself will stand wholly on the Building Owner’s land.
This is common with residential extensions.
For example, a homeowner may wish to build a single-storey side extension with the external wall positioned immediately alongside the legal boundary.
The wall may be entirely within their ownership, but because it is being constructed at the Line of Junction, the statutory notice requirements can still apply.
Does my neighbour have to agree?
Not ordinarily.
Where a new wall is being built wholly on the Building Owner’s land under Section 1(5), the Act does not require the Adjoining Owner’s consent simply to construct that wall.
However, the Building Owner must comply with the applicable statutory procedure.
This includes serving the required notice and allowing the one-month notice period to expire unless an earlier commencement is agreed.
The fact that consent is not ordinarily required does not mean the Building Owner can disregard the neighbour’s legitimate rights.
The proposed works must still comply with the Act, and other property rights remain relevant.
Building a new wall astride the boundary
The position changes considerably if the Building Owner wishes to construct a new wall partly on their neighbour’s land.
Section 1(2) allows a Building Owner to propose the construction of a new party wall or party fence wall astride the Line of Junction.
However, Section 1 does not provide an unrestricted right to occupy the neighbouring owner’s land.
Written consent is essential
Under Section 1(3), the Adjoining Owner must provide written consent if the proposed new wall is to be constructed astride the boundary.
Where consent is given within the statutory 14-day period, the wall can be constructed half on each owner’s land or in another position agreed between them.
The legislation also provides for the expenses of constructing the wall to be apportioned having regard to the use made, or to be made, of the wall by each owner.
For example, two neighbours might agree to construct a new shared masonry wall that could ultimately support buildings on both sides.
A shared wall may offer practical advantages, but the arrangement should be considered carefully because it affects both properties.
The position of the wall, the proposed construction, financial arrangements and any additional agreement should be clearly documented.
What if my neighbour refuses permission?
If the Adjoining Owner does not provide the required written consent within 14 days, Section 1(4) restricts the Building Owner to constructing the wall wholly on their own land and at their own expense.
This is an important distinction from other provisions of the Party Wall Act.
A neighbour cannot be compelled through a Party Wall Award to accept a new wall being constructed astride their boundary where the necessary consent has not been provided.
The Building Owner may need to amend the proposed design so that the new wall stands entirely within their ownership.
If the original design was based on a shared wall, the structural engineer or architect may need to reconsider the wall thickness, foundation arrangement or available internal space.
These matters are much easier to address during the design stage than immediately before construction.
Do foundations have to remain entirely within my boundary?
Not necessarily.
Section 1(6) provides a limited statutory right for a Building Owner constructing a wall wholly on their own land to place necessary projecting footings and foundations beneath adjoining land.
This right is subject to the provisions of the Act and applies within a specified period following service of the relevant notice.
It does not mean that every foundation may automatically extend into neighbouring land.
The projection must be necessary for construction of the wall, and restrictions apply to particular foundation types (Party Wall 3 metre and 6 metre rules).
What about reinforced concrete foundations?
Section 7(4) provides an important restriction concerning special foundations.
The Act defines special foundations by reference to the use of an assemblage of beams or rods to distribute a load. Reinforced concrete foundations can fall within this definition.
Special foundations cannot be placed on the Adjoining Owner’s land without their previous written consent.
This can be particularly relevant where reinforced foundations, ground beams or other engineered foundation arrangements are proposed close to a boundary.
A structural engineer should therefore establish whether the proposed foundation design remains entirely within the Building Owner’s land and whether any statutory rights or additional consents are required.
The fact that a new wall is positioned wholly within the boundary does not, by itself, resolve the position concerning its foundations.
What if the boundary position is uncertain?
This is a separate issue that can become particularly important when building directly alongside neighbouring land.
Homeowners sometimes assume that the boundary shown by a fence or the red edging on their Land Registry title plan establishes the precise legal boundary.
That is not necessarily correct.
Most registered titles in England and Wales are subject to the general boundaries rule.
The red line on a title plan usually indicates the general position of the boundary rather than its precise location.
For example, an existing timber fence may have been installed slightly within one owner’s land or moved during previous replacement work.
Constructing a permanent masonry wall against that fence without establishing the actual boundary could create difficulties.
Can Party Wall Surveyors determine the boundary?
No.
A Party Wall Award cannot conclusively determine the legal boundary between two properties.
If the boundary position is disputed, the owners may need advice from an appropriately experienced boundary surveyor and, where necessary, a solicitor.
It is therefore important to distinguish between:
A Party Wall matter: Whether the proposed construction falls within the Act and what statutory procedures apply.
A boundary dispute: Where the legal boundary is actually situated and who owns the relevant land.
Although the issues may arise together, they are not the same.
How much notice must be given?
For works under Section 1, the statutory notice period is at least one month.
A Line of Junction Notice should identify the Building Owner, describe the proposed wall and state the intended commencement date.
There is no prescribed statutory form, but the Government publishes example notices that can be used as a starting point.
A properly prepared notice should make clear whether the proposal is to construct the wall wholly on the Building Owner’s land or astride the boundary.
Should drawings accompany the notice?
Section 1 does not impose the same express requirement for plans and sections that applies to excavation notices under Section 6.
Nevertheless, including suitable drawings is good professional practice.
A clear site plan and relevant construction details can help the Adjoining Owner understand exactly what is proposed.
Where foundations are close to the boundary, it is particularly useful to show their position and construction.
This can prevent uncertainty about whether the proposed works involve any projection beneath adjoining land.
What happens if my neighbour does not respond?
The consequences depend upon the type of Section 1 notice.
Where the Building Owner proposes a new wall astride the boundary, failure to obtain written consent within 14 days means that the wall cannot be built astride the boundary under that notice.
Where the proposed wall will stand wholly on the Building Owner’s land, the Act does not require an affirmative response simply to permit that construction.
The work can ordinarily proceed after the one-month notice period, subject to compliance with the Act and any other relevant requirements.
However, a dispute may still arise about matters falling within Section 1, including the construction arrangements or compensation.
Section 1(8) provides for disputes arising under that section to be determined in accordance with Section 10.
This distinction is important because the deemed-dispute provisions for certain Party Structure and excavation notices operate differently.
Can I access my neighbour’s land to build the wall?
Access should be considered before construction begins.
Section 8 provides rights of entry in specified circumstances for works carried out in pursuance of the Act.
However, these rights are not an unrestricted entitlement to enter neighbouring land whenever it would be convenient.
The statutory conditions must be satisfied, and the Act generally requires 14 days’ notice of entry, except in emergencies.
Where access is required, it is sensible to discuss the proposed arrangements with the neighbour beforehand.
The contractor may need sufficient space to construct the wall safely, complete the external finishes or erect temporary access equipment.
Where no statutory right exists, the Building Owner will need to obtain the necessary permission.
Who pays for the new wall?
Where a wall is constructed wholly on the Building Owner’s land under Section 1(4) or 1(5), the Building Owner is responsible for the construction expense.
Section 1 also provides for compensation where damage is caused to adjoining property by the construction of the wall or qualifying projecting foundations.
Where a new party wall is constructed astride the boundary with the necessary consent, Section 1(3) contains provisions for apportioning construction expenses according to the use made or to be made of the wall.
The correct financial position therefore depends on the arrangement and the applicable statutory provisions.
It should not be assumed that every new boundary wall automatically results in a 50:50 contribution.
Practical examples for homeowners
Example 1: Side extension in Chelmsford
A homeowner proposes a side extension with a new external wall immediately alongside the boundary.
The wall will stand entirely on the homeowner’s land.
A Section 1(5) Line of Junction Notice may be required, with at least one month’s notice before construction.
The structural drawings should also be reviewed to establish whether the proposed foundations engage any additional provisions of the Act.
Example 2: Shared garden wall in Brentwood
Two neighbours wish to construct a new brick wall astride their boundary.
One neighbour proposes to arrange the work and serve notice.
The other owner provides written consent within the required period.
The wall can then be constructed in the agreed position, subject to the applicable statutory requirements and any additional agreement between the owners.
Example 3: New garage in Epping
A homeowner proposes a garage with its external wall immediately against the boundary.
The neighbour does not object to the wall but is concerned that reinforced concrete foundations may extend beneath their garden.
The foundation arrangement needs to be reviewed.
The statutory right to place necessary projecting footings does not override the restriction on placing special foundations beneath adjoining land without written consent.
Frequently asked questions
Can I build right up to my boundary?
Potentially, yes. However, you must establish the legal boundary position and comply with the Party Wall Act where applicable. Planning, Building Regulations and other property rights must also be considered.
Do I need permission to build a wall entirely on my land?
Section 1 does not ordinarily require your neighbour’s consent simply to construct a qualifying new wall wholly on your land, but a Line of Junction Notice may still be necessary.
Can my neighbour stop me building astride the boundary?
They can refuse the consent required under Section 1 for a new wall astride the boundary. Without that consent, the Act does not authorise you to construct the wall partly on their land.
Is a timber fence a party fence wall?
No. The statutory definition of a party fence wall concerns a wall separating adjoining land. Timber fences and hedges are not party fence walls under the Act.
Does planning permission override the Party Wall Act?
No. Planning permission, Building Regulations and the Party Wall etc. Act 1996 are separate legal requirements.
Do I need a Party Wall Surveyor?
You do not necessarily need to appoint a surveyor simply to serve a notice. However, professional advice can be valuable where the wall position, foundation design or statutory requirements are uncertain. If a dispute arises within the Act, the Section 10 procedure may become relevant.
Conclusion: Obtain advice before building on the boundary
Building a new wall at the boundary is not necessarily complicated, but the statutory requirements should be established before work begins.
The distinction between constructing a wall wholly on your own land and building astride the boundary is particularly important.
A Line of Junction Notice may be required in either situation, but your neighbour’s consent is essential where a new wall is to stand partly on their land.
The position of foundations, any proposed projection beneath adjoining land and the precise legal boundary should also be considered.
PJF Surveying LLP provides Party Wall services to homeowners, developers and property professionals throughout Essex and the South East.
We can review architectural and structural drawings, identify the relevant statutory requirements, prepare and serve Party Wall Notices and undertake the statutory surveyor role where a dispute arises.
If you are planning an extension, garage or new wall close to your boundary, contact PJF Surveying LLP for advice before construction begins.
Peter Furness BSc (Hons), AssocRICS, MCIOB, MFPWS
PJF Surveying LLP – RICS regulated surveying practice
Last reviewed: October 2026