Of the three types of party wall notice, Section 6 is the one most commonly missed.
Homeowners planning extensions know they might need a party wall notice if they're building on the shared wall. But Section 6 — which covers excavations near your neighbour's foundations — catches people off guard. The works might be entirely on your own land, well away from the boundary. And yet the Act still applies.
What is Section 6 of the Party Wall etc. Act 1996?
Section 6 covers "adjacent excavation" — specifically, any excavation within:
- 3 metres of a neighbouring building or structure, if the bottom of your excavation will be at the same level as or deeper than the bottom of your neighbour's foundations
- 6 metres of a neighbouring building or structure, if your excavation will cut a line drawn downward at 45 degrees from the base of their foundation
These distances are measured from the neighbouring structure — not from the boundary line. If your neighbour's house is 2 metres from the boundary, and you're excavating 1.5 metres from the boundary, you may be within the 3-metre trigger zone. For the full statutory detail on both tests, see our Section 6 pillar guide.
Does my extension need a Section 6 notice?
Almost certainly, if it's a new build extension rather than a conversion. Here's why:
A typical single-storey rear extension uses strip foundations at a depth of 900mm to 1,000mm. In most cases, this places those foundations within 3 metres of the adjoining property. The 3-metre rule is triggered by the depth relative to the neighbouring foundations, not just the horizontal distance.
If your contractor digs foundations deeper than 1 metre — as many will for clay soils, or where the engineer specifies deeper foundations — the likelihood of triggering Section 6 increases further.
The responsible approach is to check both the horizontal distance to the adjoining structure and the planned foundation depth, then apply the 3-metre or 6-metre test accordingly. Your structural engineer or architect should be able to confirm whether Section 6 applies.
What must a Section 6 notice include?
Unlike Section 3 (party structure) notices, a Section 6 notice has a specific additional requirement: drawings must accompany the notice. This is a statutory requirement, not a best practice recommendation.
The drawings need to show the location of the excavation and its proposed depth. Plans from your structural engineer or architect are typically appropriate. Without drawings, the notice is not valid.
Beyond the drawings, the notice must include:
- Your full name and address
- Your neighbour's full name and address
- The site address
- A description of the excavation works
- The depth and approximate location of the proposed excavations
- The proposed start date (minimum one month's notice for Section 6)
- Your signature and date
What's the notice period for Section 6?
One month before works start — shorter than the two-month period for Section 3 party structure notices. But it still needs to be factored into your programme. If your contractor is ready in three weeks and you haven't served notice, you have a problem.
What if both Section 3 and Section 6 apply?
This is common. A rear extension that abuts the party wall and requires foundations within 3 metres of the neighbour's building needs both a Section 3 notice and a Section 6 notice. Both can be served at the same time, to the same neighbour.
The longer notice period applies: if your Section 3 notice requires two months and your Section 6 requires one month, the two-month period governs.
What if I don't serve a Section 6 notice and I need one?
Proceeding with excavations that trigger Section 6 without serving notice is a breach of the Act. Your neighbour can seek an injunction in the County Court to stop the works — even mid-build. The courts take the Party Wall Act seriously, and injunctions are granted.
More practically: if damage occurs to your neighbour's property during excavation works that weren't notified, you lose many of the Act's protections. The formal process exists to protect both parties. Skipping it removes that protection.
Section 6 and rear-garden outbuildings
It's worth noting that Section 6 doesn't only apply to main house extensions. A large garden room, studio, or outbuilding requiring foundations within 3 metres of any adjoining structure may also trigger Section 6. The "structure" in the legislation is interpreted broadly — it doesn't have to be the main dwelling.
The Section 6 notice most people don't think about
In terraced properties, the house at the rear of the garden is sometimes overlooked. If your rear extension or outbuilding's foundations are within 3 metres of a neighbouring structure at the back — a house or outbuilding in the next street, for instance — those owners need to be notified too.
Map out all structures within 6 metres before assuming you only need to notify the neighbours on each side.
Generate your Section 6 notice today
Our system covers Section 6 adjacent excavation notices as standard, including the required works description and a checklist to confirm your drawings are ready. Not sure whether you need one? Take our free eligibility checker first.