What If My Neighbour's House Has Shallow Foundations and I am Digging Deeper?
If your excavation is within 3 metres of a neighbouring building and goes deeper than their foundations, Section 6 requires you to serve notice, and shallow foundations make that more likely. Your surveyor and the neighbour's will record the position and set protective measures in an award.
Why shallow foundations matter
Many older houses have foundations that are only a short way below ground. Any new basement, deep extension footing or drainage trench nearby can easily go deeper than that. Section 6 is triggered by depth relative to the neighbour's foundations, not by an absolute depth.
The two tests in Section 6
Notice must be at least 1 month before work starts, and must include plans and sections.
- Excavation within 3 metres of a neighbouring building or structure, going deeper than the bottom of its foundations
- Excavation within 6 metres where it cuts a line drawn at 45 degrees downward from the bottom of the neighbour's foundations
Finding out what is there
You will often not know how deep next door's foundations are. Trial pits, dug carefully and agreed with the neighbour, are the usual way to find out. Access to the neighbour's land is governed by the Act and normally needs 14 days' notice, except in an emergency.
A structural engineer usually designs the answer. That might be underpinning, a stiffer retaining wall, or a shallower scheme. The surveyor's job is to make sure the award fits the design and that the neighbour is protected.
What the award may cover
- A schedule of condition of the neighbour's house
- Method statements and sequencing, for example excavating in short bays
- Monitoring, such as crack gauges
- Security for expenses if the neighbour requests it and the surveyors agree
- Who pays the costs, normally the building owner where the work is for their benefit
If the neighbour worries
Their concern is reasonable. They can dissent and have their own surveyor, usually at your cost where the work is yours. You must compensate for damage caused and make good any damage. A careful record at the start is the best protection for both sides.
Frequently asked questions
Do I need to dig a trial pit first?
Often it is sensible, because it shows the actual depth. Agree it with the neighbour and your surveyor beforehand.
Is planning permission enough?
No. Planning and building regulations are separate from the Act. Notice is still needed.
Can the neighbour stop my project?
Not by refusing. They can dissent, which leads to an award setting how the work proceeds.
Related guides
- Understanding Section 6 of the Party Wall Act: Excavation Within 3 or 6 Metres
- Excavations and Foundational Underpinning: Party Wall Rules Explained
- Party Wall Rules for Basement Conversions
- Schedule of Condition: Why You Need One Before Building
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.