Adjacent excavation refers to any digging activity close to a neighbouring property, most commonly for laying foundations—whether for new buildings or underpinning existing structures. It can also include excavation for drains or lowering ground levels for landscaping.
Understanding how the Party Wall etc. Act 1996 applies to adjacent excavation is crucial to avoid disputes and comply with legal requirements.
Section 6(1): Excavation Within 3 Metres of a Neighbour
Under Section 6(1) of the Act, if you plan to dig within 3 metres of an adjoining owner’s property and your excavation is deeper than your neighbour’s existing foundation, you must serve a Party Wall Notice.
For example, imagine a building owner digging a new strip foundation (a simple trench filled with concrete). The neighbour’s property may have a shallow foundation typical of Victorian or older homes—often a brick spreader footing or a shallow concrete base.
Modern foundations are usually at least 1 metre deep, depending on soil and tree roots. If your new foundation extends below the neighbour’s and is within 3 metres of their structure—including garden walls, solid studios, or garages—you must notify them under this section.
This scenario is common in:
- Rear extensions
- New build houses on good soil conditions
It’s important to remember that this applies to any permanent structure next door, not just the main house.
Section 6(2): Excavation Within 6 Metres of a Neighbour
Section 6(2) applies to deeper excavations, often involving piled foundations. These are deep concrete shafts sunk into the ground to support larger buildings or where the soil is poor.
Here, the Act uses a 45-degree angle rule: if a 45° line drawn downwards from the midpoint under your neighbour’s existing foundation intersects your new foundation within 6 metres, you need to serve a Party Wall Notice.
This protects the neighbour’s foundation from potentially destabilising deep excavations nearby.
What Must a Section 6 Notice Include?
Any notice served under Section 6 must be accompanied by:
- A plan showing the site and the depth of excavation
- A site plan illustrating the proposed new structure
These details ensure the neighbour understands the extent of the works and their potential impact.
How We Can Help
We have extensive experience serving and managing Section 6 notices for various projects. Whether you are a building owner preparing to start work or a neighbour seeking advice, we’re here to guide you through the Party Wall process smoothly and professionally.
If you’d like assistance with your adjacent excavation or Party Wall Notice, feel free to reach out for expert advice.