Party Wall etc. Act 1996 Excavation Rule  

Party Wall etc. Act 1996 Act 3 metre rule explained

Party Wall etc. Act 1996 – the 3-metre rule, explained clearly

The 3-metre rule comes from Section 6 of the Party Wall etc. Act 1996. It controls excavation works close to a neighbour’s building.

What the 3-metre rule actually is

You must serve a Party Wall Notice on your neighbour if both of these apply:

1. You excavate within 3 metres of any part of their building or structure and

2. Your excavation will go deeper than the bottom of their existing foundations.

If either condition is not met, the 3-metre rule does not apply.

Why it exists

Excavating near a neighbour’s foundations can undermine or destabilise them. The Act ensures neighbours are warned, protected, and compensated if damage occurs.

Typical projects that trigger the 3-metre rule

• Rear or side extensions

• New foundations

• Basements or cellar excavations

• Structural groundworks close to the boundary

How depth is assessed (important!)

• It’s the depth of your excavation, not the finished building

• It’s compared to the lowest point of your neighbour’s foundations

• If foundation depth is unknown, surveyors usually assume shallow foundations (common in older houses)

Notice requirements

If the 3-metre rule applies, you must:

• Serve a Section 6 Notice

• Give at least 1 month’s notice before starting excavation

• Include plans, sections, and excavation depth

Your neighbour then has 14 days to:

• Consent (works can proceed)

• Dissent and appoint a surveyor

• Request an agreed surveyor

3-metre rule vs 6-metre rule (quick comparison)

Common misconceptions

• ❌ “It only applies if I touch the party wall” → False

• ❌ “Planning permission overrides it” → False

• ❌ “It’s only for terraced houses” → False

The Act applies regardless of planning permission and includes detached properties.

What happens if you ignore it?

• Your neighbour can stop the works (injunction)

• You may be liable for repair costs

• Delays and legal fees often cost far more than complying

Simple example

You’re building an extension.
Your neighbour’s house is 2.5m away.
Their foundations are 900mm deep.
Your excavation will be 1.2m deep.

✅ 3-metre rule applies → Party Wall Notice required

To request a quotation simply complete this form

Or call the Party Wall Office on 0207 1180 039 We are open 7 days a Week 9.00am to 9.00pm