Party Wall Section 6 Explained: The 3m/6m Excavation Rules

If you plan to dig new foundations for an extension, a basement, or structural piers near a neighbour’s property, Party Wall Section 6 of the Party Wall etc. Act 1996 sets out the rules you must follow. This guide explains the 3 metre and 6 metre excavation rules, how the party wall section 6 notice works, what drawings you must include, how disputes are resolved, and the practical steps that keep projects safe, lawful, and on programme.

We've translated the formal wording of the Party Wall Act to plain English as far as possible, but we cite the sections of the Act so you can check every step.

What Section 6 covers

Section 6 kicks in when you excavate within 3 metres of a neighbour’s building and dig deeper than the neighbour’s foundation level, or when you excavate within 6 metres and cut into the 45 degree plane measured from the neighbour’s foundation level and wall face.

If Section 6 applies, you must serve a party wall section 6 notice at least one month before excavation begins, with plans and sections that show depth and position. If your neighbour does not consent within 14 days, the law treats that silence as dissent and a party wall dispute arises, which surveyors resolve by award.

The legal trigger: the 3 metre rule

The 3 metre rule is the simple one. Section 6 applies where you propose to excavate within 3 metres horizontally of any part of your neighbour’s building or structure and any part of your excavation will extend below the bottom of their foundations. In short, close and deeper equals Section 6.

Party Wall Act Reference: Section 6(1)(a) and (b) set the distance and depth test.

The legal trigger: the 6 metre + 45 degree rule

The 6 metre rule is a geometry test. If you plan to excavate within 6 metres, Section 6 applies when any part of your excavation will meet a plane drawn downwards at 45 degrees from the line at the neighbour’s foundation depth, starting at the external face of their wall. Think of a diagonal zone of influence under their property. If your dig crosses that zone, you must serve a party wall section 6 notice.

Party Wall Act Reference: Section 6(2)(a) and (b) describe the 6 metre and 45 degree plane.

What the Section 6 notice must include

When Section 6 applies, you must serve written notice at least one month before you start to excavate, or excavate and erect a structure. The notice must:

Indicate your proposals and state whether you propose to underpin or safeguard your neighbour’s foundations, and

Be accompanied by plans and sections showing the site and depth of the excavation, and the site of any building or structure you intend to erect.

Party Wall Act Reference: Section 6(5) sets the one month notice and underpinning statement. Section 6(6) lists the drawings required.

Tip: Serve the party wall section 6 notice with clearly labelled plan, section and foundation depth annotations. That reduces queries and speeds up agreement.

How and when to serve the notice

You can serve notices by hand, by post, and, if the recipient has agreed to receive notices electronically and given an electronic address, by electronic communication. Serve on every adjoining owner. Keep dated proof of service.

Party Wall Act Reference: Section 15 sets out service methods, including electronic service by prior agreement. Section 20 defines “adjoining owner” for Section 6 by the relevant distances.

Timing essentials:

Minimum one month before excavation begins.

If work does not begin within 12 months, the notice ceases to have effect and you must serve again.

If the neighbour does not consent within 14 days, dissent is deemed and a dispute arises.

Party Wall Act Reference: Section 6(5) sets the one month period. Section 6(8) sets the 12 month expiry. Section 6(7) sets the 14 day deemed dissent.

What happens after you serve a Section 6 notice

Your neighbour has three broad choices:

Consent in writing. You can proceed, but you must still carry out the work with proper care and comply with other legal duties.

Dissent and appoint a surveyor. You appoint your surveyor. The two surveyors select a third surveyor.

Do nothing for 14 days. The law treats this as dissent, so a dispute arises and surveyors must be appointed.

Party Wall Act Reference: Deemed dissent is in Section 6(7). The dispute resolution framework is Section 10.

The Surveyor’s Award under Section 10

Once a dispute arises, the agreed surveyor or the two surveyors settle matters by award. The award can determine:

Your right to execute the works,

The time and manner of carrying out the excavation, including sequence and protection measures, and

Any other matter arising out of or incidental to the dispute, including costs.

Party Wall Act Reference: Section 10(10) and 10(12) set the award’s scope, and Section 10(13) deals with reasonable costs.

Practical outcomes inside a Section 6 award often include:

Method statements for temporary works and excavation support.

Requirements for condition surveys and photographic schedules before works.

Monitoring of movement or vibration during excavation.

Security for expenses if the neighbour reasonably seeks financial protection.

Party Wall Act Reference: Security for expenses is available under Section 12. The award can set time, manner, and safeguards.

Your duties to protect and make good

Section 6 gives a statutory right to excavate near a neighbour’s building, but the Act balances that right with responsibilities:

You must not cause unnecessary inconvenience.

You must compensate any adjoining owner and occupier for loss or damage resulting from works under the Act.

If you open your neighbour’s land for your works, you must provide and maintain proper hoarding, shoring, fans or temporary works.

You cannot place special foundations (reinforced foundations that distribute load through beams or rods) on the neighbour’s land without their prior written consent.

Party Wall Act Reference: Section 7(1) to 7(5). Section 20 defines “special foundations.”

The right to underpin or safeguard your neighbour’s building

Section 6 gives you the right, and if required the duty, to underpin or otherwise strengthen or safeguard the neighbour’s foundations so far as necessary. If your excavation might undermine support, you must propose suitable protection and include this in the party wall section 6 notice. The award will then settle the technical details and timing.

Party Wall Act Reference: Section 6(3) sets the underpin and safeguard right.

Access rights that make the work possible

You, your contractors, and your surveyor can access neighbouring land during usual working hours to execute works in pursuance of the Act, with proper notice. In emergencies, shorter notice applies. If premises are closed, a police officer can accompany entry and doors may be opened to allow lawful access. Serve at least 14 days’ notice for non-emergency entry.

Party Wall Act Reference: Section 8 sets access rights and notice periods.

Costs and who pays

As a starting point, the building owner pays the expenses of works under the Act. However, the surveyors can apportion costs in light of facts and the Act contains several specific rules. For example, the reasonable costs of making the award and reasonable inspections are paid as the surveyor determines, usually by the building owner. If the neighbour later benefits from work funded solely by you, the Act can require a due proportion to be repaid to you. The award will deal with this where relevant.

Party Wall Act Reference: Sections 10(13) and 11 cover costs and apportionment, with later use provisions in Section 11(11).

Common project scenarios

1) Rear extension with trench foundations at 1.2 metres deep, 2.6 metres from a neighbour

The neighbour’s 1960s strip foundation sits at 0.9 metres. You plan to dig within 3 metres and go deeper. Section 6 applies. You must serve a party wall section 6 notice with plan and section, then follow the dispute route if consent is not given in 14 days.

2) New piled extension at 4.0 metres from a neighbour

Even though 4.0 metres exceeds 3 metres, it is within 6 metres. A desk check of the 45 degree plane from the neighbour’s foundation depth shows your pile toes cross that plane. Section 6 applies. Serve the party wall section 6 notice with pile layout, pile depths, and sections.

3) Basement excavation 1.5 metres from a neighbour with shallow footings

This is within 3 metres and much deeper than the neighbour’s foundation level. Section 6 applies. Expect surveyors to require method statements, temporary works design, monitoring, and security for expenses due to higher risk.

What if your neighbour is also within 3m or 6m of you

Section 6 treats both properties as adjoining when they are within the relevant distances. In practice, both owners can be building owners and adjoining owners at the same time, each with matching rights and duties. Coordination via surveyors is key.

Party Wall Act Reference: Section 6(4) deems the owners adjoining for Section 6 when within the respective distances.

What happens if you do not serve a Section 6 notice

Proceeding without notice when Section 6 applies risks:

Injunctions that halt works,

Damages claims for loss and remedial costs, and

A strained neighbour relationship that increases project risk.

The Act also creates offences for obstructing lawful entry, and it provides civil recovery for sums due under the Act. The safest strategy is to comply fully and document everything.

Party Wall Act Reference: Offences are in Section 16. Recovery of sums as civil debt is in Section 17.

Step by step: how to do Section 6 correctly

Check distances and depths. Measure to the neighbour’s structure. Compare your proposed excavation depth to the bottom of their foundations. Apply the 3 metre and 6 metre + 45 degree tests.

Prepare drawings. Produce a site plan, sections with finished excavation levels, foundation types and depths, plus any new structure footprint. These are mandatory with a Section 6 notice.

Draft the party wall section 6 notice. State your proposals and whether you propose to underpin or otherwise safeguard the neighbour’s foundations. Serve at least one month before works.

Serve correctly. Use permitted service routes. Consider electronic service only if the recipient has agreed to it and provided an address. Keep proof.

Manage the 14 day window. If consent is not received, treat it as dissent and appoint a surveyor promptly to avoid delay.

Engage with surveyors. Provide method statements, temporary works designs, and risk assessments. The award will set the time and manner of works and any protection measures.

Deliver carefully on site. Respect access requirements, make good any damage, and avoid unnecessary inconvenience. Keep records and photographs.

FAQs: Party Wall Section 6 Notice and the 3m/6m Rules

Do I always need a party wall section 6 notice for an extension?
Only if your excavation meets the 3 metre deeper test or the 6 metre + 45 degree test relative to your neighbour’s foundations and wall face. Many rear extensions do meet one of these tests.

How long before digging must I serve the notice?
At least one month before you begin excavation. If the work does not start within 12 months of service, the notice expires and you must serve again.

What drawings must I include?
Provide plans and sections showing the site and depth of the excavation, plus the site of the new structure if you are building. Lack of clear sections is a common reason for delay.

What happens if my neighbour ignores the notice?
If they do nothing for 14 days, the Act treats this as dissent, and a dispute arises to be determined by surveyors and award.

Can my neighbour require underpinning?
Yes. You may, and if required you must, underpin or otherwise safeguard their foundations so far as necessary. This is addressed in your notice and the award.

Can I put reinforced piles or special foundations under my neighbour’s land?
Not without written consent. The Act does not authorise special foundations on adjoining land unless the neighbour agreeas in writing.

Who pays for the surveyors?
Usually the building owner pays the reasonable costs of the award and related inspections, but surveyors can apportion costs depending on the circumstances.

What if I need to go onto my neighbour’s land to dig or install supports?
The Act grants rights of entry for works in pursuance of the Act, subject to proper notice. In emergencies, shorter notice applies.

How do I serve by email?
Only if the recipient has stated a willingness to receive notices electronically and given an electronic address. Keep a record of that agreement.

What if I damage my neighbour’s property?
You must compensate the adjoining owner or occupier for loss or damage caused by works under the Act. The award can also set how making good will be handled.

Key Takeaways - Party Wall Section 6 Notice

The 3 metre rule and the 6 metre + 45 degree rule decide whether Section 6 applies. Measure carefully and check depth.

Serve a party wall section 6 notice one month before excavation and include plans and sections with depths and positions.

Silence for 14 days means dissent. Surveyors then resolve matters by award that governs time, manner, safeguards, and costs.

You must avoid unnecessary inconvenience, compensate for damage, and protect your neighbour’s foundations where needed.

Special foundations on the neighbour’s land need written consent. Do not assume permission.

Need help with your party wall section 6 notice?

Our specialists prepare compliant Section 6 notices, clear plans and sections, and manage the award process end to end. If you are planning an extension, basement, or piled foundations near a neighbour, we can help you apply the 3m/6m rules correctly, avoid delay, and protect both properties. Get in touch to discuss your project and receive a fixed-fee proposal.

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