Excavations and Foundational Underpinning: Party Wall Rules Explained
Underpinning a party wall is Section 2 work, and excavation near a neighbouring building can fall under Section 6. Notices are needed in both cases. The excavation triggers are 3 metres and 6 metres, measured from the neighbour's building.
Underpinning
Underpinning deepens or strengthens foundations by working beneath them in stages. If the foundations carry a party wall, it is work to a party structure and needs at least two months' notice. Even where you underpin only your own wall, nearby excavation may still be caught by Section 6.
The 3 metre and 6 metre rules
Section 6 applies where you excavate within 3 metres of a neighbouring building and go deeper than the bottom of its foundations. It also applies within 6 metres where your excavation cuts a line at 45 degrees down from the bottom of the neighbour's foundations.
What a notice must contain
An excavation notice needs at least one month and must include plans and sections showing the depth and location of the work, and how you propose to support the neighbouring building where needed. It lapses if work has not started within twelve months.
Why surveyors matter here
Ground movement is the main risk. The award usually deals with the following.
- A schedule of condition of the neighbour's building.
- Sequence of work and temporary support.
- Monitoring for movement.
- Access and working hours.
- Security for expenses if the neighbour asks for it and the surveyors agree.
Compensation
If the work causes damage, the building owner must compensate or make good. A thorough record before work begins is the strongest protection for both sides.
Underpinning also affects the neighbour in ordinary ways: noise, vibration, dust, and access for pumps or props. The award can set working hours and limits on plant. Raise your concerns with your surveyor early, because these points are easier to settle before work begins.
Frequently asked questions
Is any digging near a wall covered?
Only if it meets the distance and depth tests. Shallow digging outside those limits is not covered.
Can neighbours ask for money upfront?
They can ask for security for expenses. If it is disputed, the surveyors decide.
Do I need a structural engineer?
Practically yes. The surveyors will want to see the engineer's design.
Related guides
- Understanding Section 6 of the Party Wall Act: Excavation Within 3 or 6 Metres
- Party Wall Rules for Basement Conversions
- Security for Expenses: Protecting Against Unfinished Work
- What If My Neighbour's House Has Shallow Foundations and I am Digging Deeper?
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.