Understanding Section 6 of the Party Wall Act: Excavation Within 3 or 6 Metres
Section 6 of the Party Wall etc. Act applies when you excavate close to a neighbour's building. Notice is needed if you dig within 3 metres and deeper than their foundations, or within 6 metres where the excavation cuts a 45-degree line drawn from the bottom of their foundations. You must give at least one month's written notice.
The 3 metre test
If you plan to excavate within 3 metres of a neighbouring building or structure, and the excavation will go deeper than the bottom of that neighbour's foundations, notice is required.
The 6 metre test
Within 6 metres, notice is required if the excavation will cut a line drawn downwards at 45 degrees from the bottom of the neighbour's foundations. Picture a slope going down and away from the base of their footing. If your hole crosses that line, the test is met.
Because it depends on how deep the neighbour's foundations are, it is often not obvious from the surface.
What the notice must contain
Notice must be in writing, at least one month before work begins, and must describe the work. It must include plans and sections showing the site and depth of the excavation and where any new building will go. Say whether you propose to strengthen or safeguard the neighbour's foundations.
Neighbour response
The adjoining owner has 14 days to respond in writing. If they consent, work can proceed. If they dissent or say nothing, surveyors are appointed.
Where you have offered to underpin or safeguard their foundations, they can ask for that at your expense, and the award records the details.
Practical points
Foundation depth is often guessed. A surveyor may recommend trial holes or a structural engineer's input. Ground movement, water and drainage can all affect a neighbour's property, so ask for a schedule of condition before any digging starts.
Frequently asked questions
Is a garden pond an excavation?
It can be, if it is within the distances above and deep enough to meet the tests. It depends on the depth relative to the neighbour's foundations.
How much notice do I give?
At least one month before excavation starts.
Does this apply to trees or drains?
Section 6 is about excavation for a new or existing structure. Drains are a separate topic, discussed elsewhere.
Source: Party Wall etc. Act 1996 on legislation.gov.uk
Related guides
- Excavations and Foundational Underpinning: Party Wall Rules Explained
- What If My Neighbour's House Has Shallow Foundations and I am Digging Deeper?
- What If an Extension Requires Piled Foundations Near a Neighbouring Property?
- Party Wall etc. Act 1996: The Definitive Guide
Last updated: . This page is general information about the Party Wall etc. Act 1996 (England and Wales). It is not legal advice. Every property and dispute is different, so take advice from a party wall surveyor or a solicitor before you act.