Party Wall Building on the Line of Junction Explained

If you’re planning to build right up to the boundary, you’re dealing with Section 1 of the Party Wall etc. Act 1996 and the rules for Party Wall Building on the Line of Junction Explained

If you’re planning to build right up to the boundary, you’re dealing with Section 1 of the Party Wall etc. Act 1996 and the rules for party wall line of junction works. This guide breaks down the legal framework, notice strategy, neighbour responses, costs, access, and dispute resolution - plus practical examples and a step-by-step checklist.

What the “line of junction” actually is

The line of junction is the boundary line where the land of two different owners meets. Section 1 of the Act applies when either owner proposes new building on that line in two common scenarios:

The lands are not built on at the boundary; or

They are built only to the extent of a boundary wall (i.e., not a party fence wall and not an external wall of a building).

When a party wall, party fence wall, or an external wall already exists at the boundary, your project likely falls under Section 2 (and you would use a party structure notice under Section 3 rather than a Section 1 notice).

Your options under Section 1 (and when each applies)

A) Build a party wall or party fence wall astride the boundary - only with consent

You must serve a Section 1(2) notice at least one month before starting, describing the intended wall.

If the adjoining owner consents within 14 days, you can build half on each owner’s land (or as agreed); expenses are then shared in proportion to use (including future use and prevailing costs at that time).

If there’s no consent within 14 days, an astride wall is not permitted; see option B below.

B) Build a wall wholly on your own land (if consent is refused or silence)

If the neighbour refuses - or simply doesn’t reply within 14 days - you may only build wholly on your land as an external wall or fence wall, having served a one-month Section 1 notice.

You have a time-limited right to place projecting footings and foundations beneath the neighbour’s land if necessary - but only between one and twelve months after serving the notice. You must compensate for any damage.

A crucial limitation: Special Foundations

Even where projecting foundations are allowed, you cannot place special foundations (e.g., reinforced assemblies with steel) on your neighbour’s land without their prior written consent. See our detailed article on special foundations for more information.

What a valid Section 1 notice should contain

The Act requires a notice that indicates your desire to build and describes the intended wall, served ≥1 month before you start. Best practice is to include:

Building owner’s details and site address

Clear proposal: “party wall/party fence wall astride” or “wall wholly on our land on the line of junction”

Wall location, height, thickness, materials (attach plans/sections)

Proposed start date (respect the one-month minimum)

Whether projecting foundations are anticipated

Contact details and route for queries

An explicit request to consent within 14 days if you propose to build astride

Service method: you may serve by post, in person, or electronically if the recipient has agreed and provided an electronic address. Keep proof of service.

How adjoining owners can respond (and what that means for you)

Consent within 14 days (astride) → You can build a party wall/party fence wall astride the line. Costs are shared fairly over time, having regard to each owner’s use and prevailing rates at that time.

No consent / refusal → You must build wholly on your own land after the one-month period. You may use projecting footings/foundations if necessary between months 1–12 from notice, and you must compensate for damage.

Security for expenses: Either party may require security before works begin - especially prudent where projects are complex or cash-sensitive. If not agreed, surveyors determine the amount.

Costs: who pays now - and who pays later?

Astride (with consent): Each owner contributes a due proportion tied to use made or to be made, priced at prevailing rates when that use happens. Usually the building owner constructing the wall bears the initial cost, with a right to a later contribution if the neighbour uses the wall by enclosing upon it for instance.

Wholly on your land: You pay initially. If the neighbour later makes use of your wall, they must pay a due proportion, calculated as if the work were done at the time of their later use.

Damage/Disturbance: You must make good or pay compensation for loss or damage resulting from works under the Act.

Access, timing and conduct on site

The Act grants a right of entry during usual working hours for works in pursuance of the Act. Serve 14 days’ notice for non-emergencies and take proper protections (hoarding, shoring, etc.). Avoid unnecessary inconvenience, or you risk compensation claims and programme slippage.

Disputes and awards: how Section 10 protects momentum

If a dispute arises - over design particulars, access, protections, compensation, security or cost apportionment - either both parties appoint an agreed surveyor or each appoints one and they select a third surveyor. The surveyor(s) issue a binding award covering what can be done, how and when, and by whom costs are paid. Either party can appeal to the county court within 14 days of service.

Practical, real-world scenarios (to make the rules tangible)

1) Rear extension where both owners benefit (astride, by consent)

You propose a single-skin party wall to form the flank of your extension astride the line. You serve a Section 1(2) notice one month in advance; your neighbour consents within 14 days. You build half on each owner’s land. Five years later, your neighbour extends and ties in, triggering a fair contribution priced at rates prevailing at that time.

2) Garden wall where the neighbour stays silent (wholly on your land)

You propose a party fence wall astride; the neighbour does not consent. You proceed with a masonry wall wholly on your land after one month. Your strip footings need to project beneath their soil; you install them between months 1–12 post-notice and compensate for minor garden disturbance. Because you avoided special foundations under their land, no written consent was needed for projection.

3) Tight urban site with reinforcement conflicts (special foundations)

Your design calls for reinforced special foundations under the neighbour’s land. Without written consent, you cannot place them below the boundary; you must re-design to confine reinforcement within your land or opt for an acceptable footing type.

Myths we hear all the time (and the facts)

“Silence means consent to build astride.”
False. If there’s no consent within 14 days, you cannot build astride; you must build wholly on your land.

“I can put any foundations under next door if needed.”
Not quite. You have a limited window to place necessary projecting footings (months 1–12 after notice), but special foundations need written consent - no consent, no special foundations.

“Surveyors can decide where the legal boundary is.”
No. Appointed surveyors cannot determine legal title boundaries; they can only regulate works and related matters under the Act. If the boundary is genuinely in dispute, seek separate legal resolution while the surveyors manage Act-related risks and timing.

The complete party wall line of junction checklist

Confirm Section 1 applies (no party wall/party fence/external wall presently on the line; or only a simple boundary wall).

Choose your approach early:

Astride (needs neighbour’s 14-day consent), or
Wholly on your land (no consent required).

Astride (needs neighbour’s 14-day consent), orWholly on your land (no consent required).

Serve a Section 1 notice ≥1 month before start; include clear description, drawings, likely foundations, and start date.

Track the 14-day window:

Consent → proceed astride; set up cost-sharing records.
No consent/refusal → proceed wholly on your land after one month; consider if projecting footings are necessary.

Consent → proceed astride; set up cost-sharing records.No consent/refusal → proceed wholly on your land after one month; consider if projecting footings are necessary.

Check foundation design: avoid special foundations under the neighbour’s land unless you secure written consent; otherwise redesign.

Access planning: serve 14 days’ notice (non-emergency), schedule works in usual hours, and put up protections (hoarding/shoring).

Security for expenses: consider requesting or providing security to protect both sides; surveyors can fix the amount if disputed.

Dispute route ready: appoint surveyor(s) if needed and obtain an award covering method, timing, protections and costs; note the 14-day appeal window.

Cost records: retain valuations, invoices and programmes; if the neighbour later makes use of your work, recover a due proportion at prevailing rates then.

Frequently asked questions

Do I always need my neighbour’s consent?
Only if you want to build astride the boundary as a party wall/party fence wall. If consent isn’t given within 14 days, you must build wholly on your land.

Can I start immediately after serving notice?
No. You must allow at least one month from service of the Section 1 notice before starting.

Can my footings go under next door?
Yes, if necessary, but only between one and twelve months after service of your notice - and you must compensate for damage. Special foundations under their land need written consent.

What if the neighbour later uses my wall?
They owe a due proportion of your cost, calculated as if the work were done at the time they use it (not historic cost).

What happens if we disagree about method or protections?
Appoint surveyor(s) under Section 10 to issue a binding award on what may be done, how and when, including costs. There’s a 14-day appeal window.

Do I get automatic access to their land?
You have a statutory right of entry for works under the Act, but you must give 14 days’ notice (unless emergency) and avoid unnecessary inconvenience while providing proper protections.

Step-by-step timeline (from first idea to award-ready)

Concept & boundary check: Confirm Section 1 applies and whether you’ll seek consent to build astride or default to building on your land.

Engineer early: Choose foundations that minimise encroachment; if special foundations under the neighbour’s land are essential, plan for written consent - or re-design.

Serve Section 1 notice (≥1 month prior) with drawings and clear description; decide whether to allow e-service.

Manage the 14-day response: consent → astride; no consent → wholly on your land. Lock in access logistics and any security for expenses.

Pre-start: serve access notices (14 days unless emergency), agree protections, prepare a schedule of condition to streamline compensation if needed.

During works: execute strictly to the notice/award, avoid unnecessary inconvenience, and keep photo records and invoices.

Post-works: if the neighbour later makes use of your wall, recover your due proportion; serve accounts where the Act requires.

Key Takeaways - Party Wall Line of Junction

Astride needs express consent within 14 days; silence = no consent.

No consent → build wholly on your land after 1 month; projecting footings allowed months 1–12 if necessary; compensate for damage.

Special foundations under neighbour’s land = written consent only.

Access requires 14 days’ notice (non-emergency) and proper protections.

Disputes go to surveyors’ award; appeal within 14 days if needed.

Contact - Party Wall Line of Junction

If you want this to run smoothly from first sketch to completion, our expert party wall surveyors can draft watertight notices, agree awards, manage neighbour relations, and protect programme and budget on your next party wall line of junction scheme.

For advice direct from one of our Surveyors, please call our Enquiry line on 020 4534 3135.

If you would rather we called you instead, please fill in our Contact form and we will be in touch.

For a quick online quote for Party Wall advice, send us the details of your project. For more articles on all aspects of the Party Wall Act see our blog.

For advice direct from one of our Surveyors, please call our Enquiry line on 020 4534 3135.

If you are planning work that is covered by the Act, or if you have received notice of work from a neighbour and want advice on how best to protect your property please contact: