Party wall notices explained: which notice do you need?
Which Party Wall Notice Do You Need?
If your building work affects a shared wall, boundary or nearby foundations, you may need to serve a Party Wall notice before work begins.
The main notice types are:
- Line of Junction Notice: for building a new wall on or close to the boundary.
- Party Structure Notice: for work affecting an existing party wall or shared structure.
- 3-metre or 6-metre Notice: for excavation close to a neighbouring building or structure.
Some projects need more than one notice. This is common with extensions, loft conversions, basement works and structural alterations, so it is sensible to get advice before serving notice or starting work.
This article provides general guidance only and should not be treated as legal advice. Where there is uncertainty, advice should be taken from a suitably qualified party wall surveyor.
Why Party Wall Notices Matter
Party Wall notices are part of the Party Wall etc. Act 1996 process. They are used to notify adjoining owners when proposed building work may affect a shared wall, boundary or neighbouring structure.
For many property owners, the notice stage can feel like a paperwork exercise. In reality, it is an important risk management step. Serving the correct notice at the right time can help avoid disputes, delays and uncertainty once building work is ready to begin.
This is especially important in London, where properties are often close together, boundaries can be tight and older buildings may have shallow foundations. A rear extension, loft conversion or basement project can trigger Party Wall requirements, even where the work appears straightforward.
If you are unsure whether your project falls under the Act, it is worth speaking to experienced party wall surveyors in London before notices are issued.
The Three Main Types of Party Wall Notice
1. Line of Junction Notice
A Line of Junction Notice is usually required when a building owner intends to build a new wall on or at the boundary line between two properties.
This may apply where you are:
- building a new wall up to the boundary
- building a new wall astride the boundary line
- constructing a new extension close to the boundary
- replacing a boundary wall as part of a new structure
Building near a boundary is not always the same as working on an existing party wall. This is why the type of notice needs to be checked carefully.
2. Party Structure Notice
A Party Structure Notice is usually required where the proposed works affect an existing party wall, party structure or party fence wall.
This can include works such as:
- cutting into a party wall to insert beams or supports
- raising, thickening or altering a party wall
- removing a chimney breast from a party wall
- repairing or rebuilding a party wall
- underpinning or strengthening a shared structure
This notice is common with loft conversions, internal structural alterations and refurbishment projects where steels or other structural elements need to be inserted into a shared wall.
3. 3-Metre or 6-Metre Notice for Excavation
A 3-metre or 6-metre notice is usually required where excavation is planned close to a neighbouring building or structure.
This often applies where foundations are being dug for:
- rear extensions
- side extensions
- basement works
- new walls
- drainage works
- structural works requiring new foundations
Many building owners assume the Act only applies if they are physically touching a shared wall. In fact, excavation close to a neighbour’s foundations can also be notifiable.
In simple terms, a 3-metre notice may be needed where excavation is within 3 metres of a neighbouring building or structure and will go deeper than the neighbour’s foundations. A 6-metre notice may be needed for deeper excavations where the proposed excavation falls within a defined distance and angle from the neighbouring foundations.
How to Know Which Notice Applies to Your Project
The right notice depends on the details of the work, not just the project name. A “rear extension” or “loft conversion” does not automatically require one single notice type. The design, boundary position, structural work and excavation depth all matter.
Common examples include:
- Rear extensions
These may require a Line of Junction Notice if a new wall is being built on or close to the boundary. They may also require a 3-metre or 6-metre notice if foundations are close to and deeper than a neighbouring structure’s foundations. - Loft conversions
These may require a Party Structure Notice if beams, steels or other structural elements are being inserted into a party wall. - Basement works
These often need careful review because they can involve excavation, underpinning and structural risk close to neighbouring buildings. - Chimney breast removal
If the chimney breast is on a party wall, its removal may require a Party Structure Notice.
For a wider overview of the process, Squarepoint’s Party Wall guide provides further practical guidance.
Can More Than One Party Wall Notice Be Needed?
Yes. One project can include several elements that fall under different parts of the Act.
For example, a rear extension may involve building close to the boundary, excavating foundations near the neighbour’s property and cutting into an existing party wall. In that situation, it may not be enough to issue one generic notice. The notices need to match the actual works.
This is where professional judgement matters. Serving the wrong notice, or missing one altogether, can create avoidable delays and may undermine confidence with the adjoining owner.
When Should a Party Wall Notice Be Served?
Timing depends on the type of notice being served. As a general guide, Party Structure Notices are usually served at least two months before the relevant works begin, while Line of Junction and adjacent excavation notices are usually served at least one month before the relevant works begin.
However, it is sensible not to leave notices until the last minute. Delays can happen if drawings are incomplete, the wrong notice has been prepared, the adjoining owner dissents, or a Party Wall Award needs to be agreed before works start.
If your project has a fixed start date, party wall matters should be reviewed well before the contractor is ready to begin.
What Happens After a Party Wall Notice Is Served?
Once notice has been served, the adjoining owner can respond. What happens next depends on the type of notice and the nature of the works.
For Party Structure Notices and 3-metre or 6-metre excavation notices, the adjoining owner can usually consent or dissent. If they do not provide written consent within 14 days, a dispute is generally deemed to have arisen under the Act and surveyors may need to be appointed.
For Line of Junction Notices, the position depends on whether the building owner proposes to build wholly on their own land up to the boundary, or astride the boundary as a new party wall. If the proposed wall is astride the boundary, the adjoining owner’s written consent is needed. If consent is not given, the building owner cannot build the wall astride the boundary and may need to build wholly on their own land instead.
This is why silence should never simply be treated as approval. The response process and next steps need to be handled correctly.
It is also worth noting that dissent does not necessarily mean the adjoining owner is trying to stop the works. In many cases, it means they want the formal protections of the Act, including a Schedule of Condition and Party Wall Award.
Squarepoint also provides party wall advice for adjoining owners who have received a notice and are unsure how to respond.
What Are a Schedule of Condition and Party Wall Award?
A Schedule of Condition is a written and photographic record of the relevant parts of the adjoining owner’s property before works begin. It can be important if damage is alleged later, as it gives both parties a clear record of the property’s condition before the building work took place.
A Party Wall Award is a formal document prepared by the appointed surveyor or surveyors where a dispute has arisen under the Act. It usually sets out what works are covered, how they may be carried out, any protective measures required and what happens if damage occurs.
The Award does not replace planning permission or building control approval. It deals specifically with party wall matters arising from the proposed works.
What Happens If You Serve the Wrong Notice?
Serving the wrong notice can cause practical problems, especially if the issue is only discovered shortly before works are due to start.
Possible consequences include:
- the notice may need to be re-served
- the statutory notice period may need to restart
- the adjoining owner may lose confidence in the process
- the project start date may be delayed
- disputes may become more likely
The risk is not just paperwork. A weak notice process can create uncertainty at exactly the wrong time, when contractors, budgets and timelines are already committed.
If works start without the correct party wall procedure being followed, the position can become more difficult. Squarepoint’s guide to failure to serve a Party Wall notice explains why this should be avoided.
Speak to Squarepoint Before Serving a Party Wall Notice
You do not always need a surveyor to serve notice, but professional advice can be valuable where there is uncertainty.
A party wall surveyor can help check whether the Act applies, identify which notice or notices are required, review drawings, advise on timing and reduce the risk of avoidable disputes.
If you are planning an extension, loft conversion, basement or structural alteration, Squarepoint Chartered Surveyors can advise whether the Party Wall etc. Act applies and which notice may be required.
For practical advice before serving notice, speak to Squarepoint and discuss your project with an experienced party wall surveyor.
Author: Scott Buchanan