What Is the Difference Between a Party Wall and a Boundary Wall?

When it comes to property ownership in England and Wales, understanding the distinctions between different types of walls on or near property boundaries is crucial—especially for homeowners, developers, architects, and surveyors. One of the most common areas of confusion lies in distinguishing between a party wall and a boundary wall. This article explores what each term means, their legal implications under the Party Wall etc. Act 1996, and how to handle common disputes involving them.

What Is a Party Wall?

A party wall is a wall that stands astride the boundary of land belonging to two (or more) different owners and is used by both owners. According to the Party Wall etc. Act 1996, the term “party wall” covers two main scenarios:

Type A – A wall that forms part of a building and stands on lands of different owners to a greater extent than the projection of any footings or supports.

Type B – A wall that separates two buildings and is jointly owned, even if it is entirely on one owner's land but used by both.

In short, a party wall:

Is shared by two adjoining properties.

May sit astride the boundary line or be entirely on one owner's land but serve both.

Comes under the legal framework of the Party Wall etc. Act 1996.

Examples of party walls include:

The dividing wall between two semi-detached houses.

The shared wall between two terraced homes.

A garden wall built jointly and used to separate backyards (but only if it meets the Act’s criteria).

What Is a Boundary Wall?

A boundary wall, on the other hand, is a wall that marks the legal boundary between two properties but is not necessarily shared or jointly owned. It may:

Be built entirely on one party’s land.

Be used only by one party.

Not serve any structural or enclosure purpose for the neighbouring property.

In legal terms, the owner of the boundary wall is solely responsible for its construction, maintenance, and any associated liabilities. It is not automatically subject to the Party Wall etc. Act 1996.

A boundary wall could be:

A standalone brick wall along the edge of a garden.

A fence wall (not forming part of a building) constructed by one owner with no contribution from the neighbour.

Where a wall is not used by both properties or is entirely within the boundary of one property, it is not a party wall.

Legal Definitions Under the Party Wall etc. Act 1996

The Act defines relevant terms as follows:

Party Wall: A wall which stands on lands of different owners and either forms part of a building or separates buildings belonging to different owners.

Party Fence Wall: A wall (not part of a building) that stands on land of different owners and is used to separate their adjoining land, typically in gardens.

Boundary Wall: Not specifically defined in the Act, but understood to be a wall erected wholly on the land of one owner, often marking the legal property boundary.

Legal and Practical Differences

Ownership	Joint or shared ownership	Sole ownership
Use	Serves both properties	Serves one property only
Location	Straddles the boundary or lies entirely on one side	Typically lies entirely on one side of the boundary
Covered by Party Wall Act?	Yes	No (unless it becomes part of a party wall later)
Rights of Access	Governed by Party Wall Act	No automatic rights for neighbour
Consent Required?	Yes, for most work under the Act	No, unless work impacts neighbouring land

Can a Boundary Wall Become a Party Wall?

Yes. A boundary wall can become a party wall if:

A neighbour decides to build against it and shares its use structurally.

Both parties agree to its shared use.

The wall is extended, raised, or rebuilt as part of a joint project.

However, this transition must be done with proper legal notice and agreement. Once shared use is established, the Party Wall etc. Act may apply.

Common Scenarios and Disputes

1. Building Along a Boundary

If a building owner wishes to construct a wall on the line of junction between two pieces of land, they can:

Build it wholly on their own land, or

Propose a party wall subject to consent from the adjoining owner (under Section 1 of the Act).

If no consent is given, the wall must be built on the builder’s own land.

2. Raising or Altering a Party Wall

A property owner may want to raise the height of a party wall for a loft extension or similar project. The Act allows this under Section 2 but requires formal notice and may require an award from surveyors if the neighbour dissents.

3. Repair Responsibilities

With party walls, both owners generally share responsibility for repairs. For boundary walls, only the owner who built it is responsible.

4. Encroachments and Trespass

If a wall is mistakenly built over a boundary line onto a neighbour’s land without agreement, this may constitute a trespass and can lead to legal action.

Surveying and Legal Considerations

Surveyors play a crucial role in identifying whether a wall is a party wall or a boundary wall. Boundary lines can be unclear, particularly in older properties or where the Land Registry plan lacks precision. Surveyors may:

Examine title deeds, conveyances, and historical OS maps.

Conduct a site survey to check physical boundaries.

Recommend a determined boundary application to HM Land Registry in contentious cases.

Importance for Homeowners and Developers

Understanding the difference is vital for:

Homeowners, to know their rights and obligations before carrying out works.

Developers, to avoid costly delays, injunctions, or compensation claims.

Surveyors, to ensure correct notices and procedures are followed.

Neighbours, to protect their property from encroachment or damage.

FAQs: What Is the Difference Between a Party Wall and a Boundary Wall?

Is a party wall always on the boundary line?

Not necessarily. A party wall may be wholly on one side’s land but used by both owners, making it a shared structure.

Can a boundary wall be shared?

Only if both owners agree to share it and use it structurally. At that point, it becomes a party wall or party fence wall.

Do I need permission to build on the boundary line?

Yes, under Section 1 of the Party Wall Act, you must serve notice and may need your neighbour’s consent depending on the wall's type.

How do I know if a wall is a party wall?

A surveyor can help you determine this based on legal definitions, physical location, and use.

What happens if I damage a party wall?

You may be liable for repairs and compensation under Section 7 of the Party Wall Act.

Can my neighbour stop me building a wall on the boundary?

They can withhold consent for a shared wall, but not if you are building entirely on your land (subject to other planning rules).

Can I use my neighbour’s boundary wall for support?

Not without their consent. Doing so may constitute trespass or structural interference.

Key Takeaways

A party wall is shared between neighbours and governed by the Party Wall etc. Act 1996.

A boundary wall is usually owned and maintained by one party and does not fall under the Act.

Consent and proper notice are crucial before undertaking works involving shared or boundary-adjacent walls.

Misunderstanding the difference can lead to disputes, delays, and legal action.

Surveyor advice is essential when dealing with unclear boundaries or older properties.

Get in Touch

If you need help or guidance on any aspect of Party Walls, our expert surveyors can help. We provide clear advice, efficient service, and compliant documentation to support your project every step of the way.

For advice direct from one of our Surveyors, please call our Enquiry line on 020 4534 3135.

If you would rather we called you instead, please fill in our Contact form and we will be in touch.

For a quick online quote for Party Wall advice, send us the details of your project. For more articles on all aspects of the Party Wall Act see our blog.

For advice direct from one of our Surveyors, please call our Enquiry line on 020 4534 3135.

If you are planning work that is covered by the Act, or if you have received notice of work from a neighbour and want advice on how best to protect your property please contact: