Party Wall Act 3 Metre Rule: When Do You Need to Serve Notice?
The Party Wall Act 3 metre rule applies when you plan to excavate within 3 metres of a neighbouring building or structure and any part of your excavation will go deeper than the bottom of your neighbour’s foundations. If this applies, you usually need to serve a Section 6 Party Wall Notice at least one month before the excavation work starts.
Does the 3 Metre Rule Apply to Your Project?
The 3 metre rule may apply if all three of the following points are relevant.
1. The excavation is within 3 metres of a neighbouring structure
This could include a neighbouring house, extension, garage, boundary wall or other structure close to the proposed excavation.
2. You are carrying out excavation works
This may include excavation for new foundations, drainage trenches, underpinning, basement works, retaining walls or similar works.
3. The excavation will go deeper than the neighbour’s foundations
The rule is not triggered by distance alone. The proposed excavation must also go deeper than the bottom of the adjoining owner’s existing foundations.
Simple rule: if the excavation is within 3 metres and deeper than the adjoining owner’s foundations, a Section 6 Notice is usually required.
Advice for Building and Adjoining Owners
| Party | What You Should Check | When to Take Advice |
|---|---|---|
| Building Owner | If you are the building owner, you should check whether your proposed excavation is within 3 metres of a neighbouring structure and whether it will go deeper than your neighbour’s foundations. You should do this before starting works. Serving the correct notice early can help avoid delays, disputes and problems once your builder is ready to begin. | You may need professional advice if you are unsure:
|
| Adjoining Owner | If your neighbour has served a Section 6 Notice, or you believe they are excavating close to your property, you should ask to see drawings showing the depth, position and distance of the proposed excavation. | You should check whether:
If you are unsure, it is sensible to take advice before responding to the notice. |
Why Use Harding Chartered Surveyors?
Harding Chartered Surveyors advises building owners and adjoining owners on Party Wall matters across London and the South East.
Our surveyors can assist with:
- checking whether the 3 metre rule applies;
- reviewing plans and excavation details;
- preparing and serving Section 6 Notices;
- responding to notices served by neighbours;
- advising building owners and adjoining owners;
- preparing Party Wall Awards where required.
If you are unsure whether your project falls within the Party Wall Act, getting advice early can help avoid unnecessary delay once works are due to begin.
Get Advice on the 3 Metre Rule
Written & Reviewed by Jeremy Goldney
Party Wall and Boundary Surveyor
MFPWS MPTS
Last reviewed: May 2026
Is the 3 Metre Rule the Same as the 6 Metre Rule?
No. The 3 metre rule and 6 metre rule are separate tests under the Party Wall etc. Act 1996.
The 3 metre rule is generally relevant where excavation is within 3 metres of a neighbouring structure and deeper than the neighbour’s foundations.
The 6 metre rule can apply to deeper excavation works, such as basements or piled foundations. This is covered separately in our guide to the Party Wall Act 6 metre rule.
Party Wall 3 Metre Rule FAQs | |
Does the Party Wall Act apply if I am building entirely on my own land? | Yes, it can. The Party Wall Act may apply even where the works are entirely on your own land if excavation is within 3 metres of a neighbouring structure and deeper than the neighbour’s foundations. |
How is the 3 metres measured? | The 3 metres is measured horizontally from the neighbouring building or structure to the proposed excavation. |
Do I need a Party Wall Notice for a rear extension? | Often, yes. Rear extensions commonly involve new foundations close to neighbouring structures. Whether notice is required depends on the distance and depth of the proposed excavation. |
Do I need a Party Wall Notice for drainage works? | Possibly. If the drainage trench is within 3 metres of a neighbouring structure and deeper than the neighbour’s foundations, a Section 6 Notice may be required. |
Can my neighbour stop the works? | Your neighbour cannot usually stop lawful works simply because they dislike them. However, if the Party Wall Act applies, the correct notice and dispute process should be followed before notifiable works proceed. |
How much notice is required for excavation works? | For excavation works under Section 6 of the Party Wall etc. Act 1996, notice is usually served at least one month before the proposed start date. |
What happens if my neighbour ignores the notice? | If the adjoining owner does not respond within the required period, a dispute is usually deemed to have arisen. Surveyors may then need to be appointed so the process can continue. |
Do I always need drawings with a Section 6 Notice? | For excavation notices, drawings are usually very important. They help show the position and depth of the proposed excavation in relation to the adjoining owner’s structure. |
