Richard Hourican |
If you are planning foundations, drainage, piling, underpinning-related works or a basement near a neighbouring property, Party Wall Section 6 is often one of the most important parts of the Act to check early. In simple terms, it deals with excavation and construction close to adjoining buildings, and it may require formal notice before work begins. This guide explains the 3 metre rule, the 6 metre rule, when a Section 6 notice is usually needed, and what happens if a neighbour dissents or does not reply.
3 Metre Rule
May apply where excavation is within 3 metres of a neighbouring building or structure and goes deeper than the bottom of the adjoining foundations.
6 Metre Rule
May apply where excavation is within 6 metres and falls within the 45 degree line taken from the bottom of the adjoining foundations.
Notice Period
A Section 6 notice is generally served at least one month before the planned excavation start date.
Response Window
The adjoining owner usually has 14 days to consent. No reply or dissent normally means a dispute has arisen.
What is Party Wall Section 6?
Section 6 of the Party Wall etc. Act 1996 covers excavation and construction close to neighbouring buildings or structures in England and Wales. It is commonly relevant where a building owner proposes new foundations for a rear extension, side return extension, basement excavation, retaining structure, drainage trench, or other structural work close to an adjoining owner’s property.
It is important not to confuse the Party Wall Act with planning permission or Building Regulations approval. These are separate regimes. Even where a scheme has planning consent and building control approval, the Act may still require notice to be served and the statutory procedure to be followed. For a broader overview, see our guide on what the Party Wall Act is.
The 3 metre rule explained
The first and more familiar Section 6 trigger is the 3 metre rule. In general terms, Section 6 may apply where you propose to excavate within 3 metres of any part of a neighbouring building or structure and any part of your excavation will go below the bottom of the adjoining foundations.
This often affects standard London residential projects, particularly rear extensions and side return works where new trench-fill foundations are being dug close to a shared boundary. It can also arise with deep drainage runs, retaining walls and similar works depending on the depth and position of the excavation.
The 6 metre rule and the 45 degree test
Section 6 can also apply even where the excavation is more than 3 metres away. This second test is commonly referred to as the 6 metre rule. It may apply where excavation is within 6 metres of a neighbouring building or structure and the proposed excavation falls within a line drawn downwards at 45 degrees from the bottom of the adjoining owner’s foundations.
In practice, this second test is often relevant for deeper foundations, piled schemes and basement works. It is usually not something that should be guessed at on site. It is better reviewed against proper drawings and sections so the position is clear before works start.
If your project involves deeper excavation near an adjoining property, our Party Wall Survey for Excavations in London service can help determine whether the Section 6 procedure is likely to apply.
Section 6 Trigger Comparison Table
| Test | Distance | Depth / Geometry | Typical Projects | Usual Next Step |
|---|---|---|---|---|
| 3 metre rule | Within 3 metres of a neighbouring building or structure | Excavation goes below the bottom of the adjoining foundations | Rear extensions, side returns, drainage trenches, retaining walls | Review drawings, confirm likely foundation relationship, and serve notice if the test is met |
| 6 metre rule | Within 6 metres of a neighbouring building or structure | Excavation falls within the 45° line from the bottom of the adjoining foundations | Basements, piled foundations, deeper structural schemes | Carry out a measured assessment using plans and sections, then serve notice if the test is met |
When do you usually need to serve a Section 6 notice?
If either Section 6 test applies, the building owner will usually need to serve a formal notice at least one month before the planned starting date for the relevant excavation. A compliant notice should not be left until the last minute. In practice, it is usually best to review the architectural and structural drawings early, identify the correct adjoining owners, and serve notice with enough time to avoid delay.
If you need support with drafting and serving notices properly, see our Party Wall Notices in London service.
What should a Party Wall Section 6 notice include?
A Section 6 notice should clearly describe the proposed excavation and construction works, identify the site address, and include the intended start date. It should also be accompanied by sufficient plans and sections showing the location and depth of the proposed excavation and, where relevant, the position of any new building or structure.
Unclear notices are one of the most common causes of delay. Where drawings are vague or the depth information is incomplete, adjoining owners are more likely to have concerns and surveyor appointment can become slower than it needs to be.
What happens after the notice is served?
Once the notice has been served, the adjoining owner can consent, dissent, or fail to reply. If the adjoining owner gives written consent, the project can usually proceed in accordance with the Act and any agreed terms. If they dissent, or do not respond within 14 days, a dispute is usually deemed to have arisen under the Act.
At that stage, surveyor appointment is normally required. The parties may agree to use one surveyor, known as an agreed surveyor, or they may each appoint their own surveyor. You can read more about the agreed surveyor role, the building owner’s responsibilities, and guidance for the adjoining owner.
What is a Party Wall Award in a Section 6 matter?
Where a dispute has arisen, the surveyor or surveyors usually resolve the matter by preparing a Party Wall Award. The Award commonly deals with the timing and manner of the works, access arrangements, protective measures, and the rights and obligations of the parties under the Act.
If you would like more detail on that stage of the process, visit our Party Wall Awards page.
Common projects where Section 6 may apply
Section 6 often needs to be considered for residential and mixed-use projects across London, particularly where excavation is close to existing neighbouring structures. Typical examples include:
- single-storey rear extensions with new foundations close to the boundary;
- side return extensions in terraced or semi-detached properties;
- basement excavations, retaining walls and underpinning-related works;
- piled foundations and deeper structural schemes;
- deep drainage runs or associated excavation near adjoining buildings.
Common Project Types and Whether Section 6 May Apply
| Project Type | Likelihood of Section 6 Being Relevant | Comment |
|---|---|---|
| Single-storey rear extension near the boundary | Often relevant | Commonly arises where the new foundations are close to the neighbour and deeper than their existing foundations. |
| Side return extension in a terrace | Often relevant | Especially common in London where adjoining foundations may be shallow and close to the proposed excavation line. |
| Basement excavation | Very often relevant | Usually requires careful review of both the 3 metre and 6 metre tests. |
| Deep drainage run near adjoining property | May be relevant | Depends on route, depth, and relationship to neighbouring foundations. |
| Piled foundation scheme | May be relevant | Often needs a site-specific assessment because geometry and depth are critical. |
| Internal refurbishment with no qualifying excavation | Usually not under Section 6 | Other parts of the Act may still need to be reviewed depending on the proposed works. |
Section 6 and basement works
Basement schemes are one of the clearest examples of why Section 6 should be reviewed early. They often involve deeper excavation, more complex structural sequencing, and a higher level of neighbour concern. In many cases, both the notice procedure and a detailed schedule of condition are sensible parts of the process.
For project-specific support, see our Party Wall Survey for Basement Works service and our Schedule of Condition Surveys page.
Why early advice matters
Section 6 issues are often less about the wording of the Act and more about timing, coordination and communication. A compliant notice served too late can affect the programme. Incomplete information can increase neighbour concern. Starting qualifying works without following the correct process can create avoidable dispute and delay.
Early review by an experienced surveyor can help identify whether the Act is likely to apply, confirm which neighbouring owners should be notified, and keep the process professional and neighbourly.
Section 6 Timeline at a Glance
| Stage | What Usually Happens | Typical Timing |
|---|---|---|
| 1. Review the drawings | Check whether the 3 metre rule or the 6 metre / 45° test is likely to apply. | Before notices are drafted |
| 2. Serve notice | Issue the Section 6 notice with plans and sections showing the proposed excavation and depth. | At least 1 month before the planned start date |
| 3. Await response | The adjoining owner can consent, dissent, or fail to reply. | 14 days from service |
| 4. If consent is given | Works may usually proceed in line with the Act and any agreed arrangements. | After the notice period or as agreed |
| 5. If dissent or no reply | A dispute is deemed to have arisen and surveyor appointment is normally required. | After the 14 day response period |
| 6. Award stage | The surveyor or surveyors prepare a Party Wall Award dealing with the timing and manner of the works. | Before relevant works proceed where a dispute exists |
What we usually need to assess a Section 6 matter
- site address and neighbouring property details;
- architectural drawings and site plan;
- foundation layout, depths, sections and structural details;
- proposed start date;
- any basement, piling, retaining wall or drainage information;
- details of previous notices or neighbour correspondence, if any.
Frequently Asked Questions
Richard Hourican, Company Director
BSc (Hons). HND Build. MCIOB. C.Build E MCABE. ARICS. MFPWS. MPTS
As a specialist Party Wall surveyor, Richard Hourican will protect your interests during building works.
Are you planning a building project – perhaps an extension, loft conversion or basement – that is on or adjacent to your property’s boundary line? Or has a ‘Party Wall’ notice dropped on the doormat informing you of a neighbour’s impending works?
It’s essential to understand all the implications of building plans. If you don’t, it could cost thousands. Our job is to ensure everything is done correctly – and that it doesn’t!
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