When do you need a Party Wall Agreement? The Rules
The short answer is that you’ll need a Party Wall Agreement when the building work you plan to carry out affects a shared wall, boundary line, or your neighbour’s foundations. The types of works involved typically include cutting into a party wall, building on or up to the boundary or excavating within 3–6 metres of a neighbouring property.
A common misconception among homeowners is that their builders, carrying out the works, will handle this or consider the legalities here for them. Do not assume this – builders are not responsible for handling anything to do with the Party Wall etc. Act 1996. Builders are not legally allowed to serve Party Wall Notices; the Building Owner (you) or a Party Wall Surveyor must serve them on your behalf.
The Party Wall Act exists for a reason
The Act is designed to protect you and your neighbour when construction work has the potential to affect both properties. It sets out a fair, legal process so that:
- Your neighbour is notified properly
- Surveyors record the condition of both homes
- Any damage is handled professionally
- Everyone has clarity before work begins
If any part of your project fits into the categories below, you’ll be required to serve a notice and, if your neighbour does not consent, obtain a Party Wall Agreement (also called a Party Wall Award).
1. When you’re working on a shared wall
If you share a wall with your neighbour (typically in semi-detached or terraced houses), it’s called a party wall, and certain types of work require an agreement.
You’ll need one if you plan to:
- Cut into the wall to insert beams (common in loft conversions)
- Remove or alter a chimney breast
- Raise, thicken, demolish or rebuild the wall
- Remove projections or features from the wall
- Add any structural support to the party wall
In simple terms: if you’re touching or altering the shared wall, the Act applies.
2. When you’re building on or up to the boundary
Even if the wall is built entirely on your land, you still need to serve notice if your new structure is going:
- Right up to the boundary line, or
- Directly on the boundary
This covers new extensions, garage walls, garden walls, and any structure that sits on the dividing line between the two properties. This part often surprises homeowners, but it’s essential because the new structure could affect the neighbour’s land, foundations, or drainage.
3. When you’re excavating near your neighbour’s foundations
If you’re digging:
- Within 3 metres of your neighbour’s home and deeper than their foundations, or
- Within 6 metres, and the excavation falls within a 45° angle of their foundation
…then you need a Party Wall Agreement.
This applies to projects like:
- Rear and side extensions
- Basement works
- Foundations for new structures
- Underpinning
- Deep drainage or soakaway installations
Excavation is one of the biggest risk factors for neighbouring properties, so the Act requires the Award to set out protective measures.
Planning an extension or basement in Surrey or London? Get a party wall quote from Westville Associates.
When you won’t need a Party Wall Agreement
Some everyday work is exempt from the Act, including:
- Replastering
- Drilling for shelves or cabinets
- Internal refurbishments
- Redecoration
- Rewiring
If the work does not affect the structure or stability of a shared wall or boundary, no notice is required.
If you’re unsure whether your project needs a Party Wall Agreement, Westville Associates can help you assess your plans and guide you through the legal process.
Next Step
If you would like to talk to Simon about your party wall, then please contact him here or simply call 07834 761 411. We cover all of Surrey, Hampshire and London.
