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You've drawn up plans for your extension or basement, but before the first shovel hits the dirt, you must address the one area of building work that poses the greatest risk to your neighbour’s property, and that is the foundation.
Foundation work, though unseen, is governed strictly by the Party Wall etc. Act 1996. Specifically, Section 6 of the Act outlines clear rules for excavation and construction of new foundations near a neighbour’s structure.
To ensure legal compliance and avoid costly disputes, every homeowner must understand two critical rules: the 3-metre rule and the 6-metre rule. This guide will demystify Section 6, detailing the specific criteria for these rules and explaining exactly when you must serve a Party Wall Notice for your new foundations.
The 3-metre rule is the most common trigger for a Party Wall Notice when building a standard rear or side extension.
You must serve a Section 6 Notice if you plan to excavate for new foundations (or construct a new building/wall) within 3 metres of your neighbour's building or structure.
However, distance alone is not enough; a crucial depth check is also required:
If your project satisfies both the 3-metre distance and the depth test, you must serve a Section 6 Notice.
The risk here lies in the potential for lateral shift and damage. By digging deeper than your neighbour's foundation close to their property, you risk removing the earth support that is holding up their structure, potentially causing subsidence or major cracking. The Section 6 Notice and subsequent Award are designed to mitigate this precise risk.
The 6-metre rule applies to excavations that are deeper and wider, typically associated with basements or piled foundations.
You must serve a Section 6 Notice if you plan to excavate within 6 metres of your neighbour’s building.
This rule focuses on geometry and depth using the 45-Degree Rule:
If the 45-degree angle line from your neighbour’s foundation base crosses into your excavation zone, you have triggered the 6-metre rule.
Since this rule is often triggered even if the excavation is more than 3 metres away, it is the primary concern for projects involving basement conversions or the installation of deep piling. If the 6-metre rule is triggered, you must serve a Section 6 Notice to legally protect both properties.
If your project triggers either the 3-metre or the 6-metre rule, you must serve the statutory notice.
The Notice of Adjacent Excavation and Construction must be served to your neighbour a minimum of one month before the work begins. The Notice must clearly state:
Crucially, the Notice must be accompanied by plans and sections detailing the excavation so your neighbour (or their surveyor) can accurately assess the risk.
Once the notice process concludes with an agreed or awarded document, the Party Wall Award will detail the protective measures needed:
Ignoring the requirements of Section 6 is one of the quickest ways to bring a construction project to a costly halt:
When it comes to foundation work, homeowners should never guess the distance or the neighbour's foundation depth. The penalty for non-compliance is simply too high.
The moment foundation plans are drawn up, you should engage an experienced Party Wall Surveyor (like those at Party Walls Limited). They will accurately measure the distances, interpret the required depth checks, and ensure correct compliance with Section 6, providing peace of mind for both you and your neighbour.
Q1: How do I accurately measure the 3-metre or 6-metre distance?
A: The distance is measured horizontally from the nearest edge of your proposed excavation/foundation to the nearest part of your neighbour’s structure or foundations. A surveyor will use your drawings and knowledge of the area to confirm accuracy.
Q2: Does the 3-metre rule apply if my new foundations are shallower than my neighbour’s existing ones?
A: No. For the 3-metre rule to apply, your planned excavation must be both within 3 metres and intended to be taken to a lower depth than the base of their foundations. If your excavation is shallower, the Section 6 notice is generally not required.
Q3: How many days advance notice do I need to give for foundation work under Section 6?
A: You must serve a Section 6 Notice (Notice of Adjacent Excavation and Construction) a minimum of one month before you intend to begin the excavation or foundation work.
Q4: What happens if I start digging foundations without serving a Party Wall Notice?
A: Your neighbour can legally treat the work as unauthorised and seek an injunction to stop the excavation. You become solely liable for any resulting damage and lose the protection of the Act.
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