The 3 Metre and 6 Metre Rules: Section 6 Excavation Notices Explained

Section 6 of the Party Wall etc. Act 1996 catches more projects than any other part of the Act — and it is the one homeowners most often miss, because it has nothing to do with touching a shared wall. If you are digging near a neighbour's building, you may need to serve notice even if your works are entirely on your own land.

The 3 metre rule (Section 6(1))

You must serve notice if you are excavating within 3 metres of a neighbouring owner's building or structure, and any part of that excavation will go deeper than the bottom of their foundations.

In practice: a standard 1 m trench fill foundation for a rear extension on a Victorian terrace in Reading, Bristol or Oxford almost always goes deeper than the neighbour's shallow Victorian footings. Notice required.

The 6 metre rule (Section 6(2))

You must serve notice if you are excavating within 6 metres of the neighbouring building and any part of the excavation falls below a line drawn downwards at 45 degrees from the bottom outer edge of their foundations.

This one catches deep pads, piles, basements and lift pits. If you are going deep, measure it — do not eyeball it.

Worked examples

• Swindon rear extension, 900 mm trench fill, 1.2 m from the boundary and 2 m from the neighbour's wall. Neighbour's footings are 600 mm. Within 3 m and deeper: Section 6 notice required.
• Bath basement dig, 2.5 m deep, 5 m from the neighbouring house. Within 6 m and well below the 45° line: Section 6(2) notice required.
• Detached Summertown property, new garage base 8 m from any neighbouring structure. Outside both distances: no notice required.
• Chippenham conservatory on a 300 mm raft, neighbour's footings at 700 mm. Within 3 m but shallower: no Section 6 notice — though a Section 1 or 2 notice may still apply.

What the notice must contain

A Section 6 notice is not a letter. It must state the intended works, include plans and sections showing the site and depth of the excavation, and state whether you propose to underpin or otherwise strengthen the adjoining foundations. Notices missing the drawings are invalid — the single most common reason a neighbour's surveyor rejects a DIY notice.

Timing

One month's notice for Section 6 (compared with two months for Section 2 works to the wall itself). The neighbour then has 14 days to consent or dissent; silence is a deemed dispute — see what happens if my neighbour ignores my notice.

Why it matters more on our patch

Shallow Victorian and Georgian footings are the norm across Bath, Bristol, Oxford, Cheltenham and central Reading — often only 300–600 mm deep on soft ground. Modern building-regulation foundations go far deeper, so nearly every extension next to period stock triggers Section 6. In the Cotswolds, rubble-filled stone footings make a photographic Schedule of Condition doubly worthwhile.

Fixed fees

First notice £50, each additional notice £30, Agreed Surveyor £650, full Award £850, standalone Schedule of Condition £350 (free with an Award). Run the 60-second checker with your postcode and dig depth and we'll confirm whether Section 6 applies before you commit.

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