Section 1 of the Party Wall Act: Building a New Wall on the Boundary - A UK Homeowner's Guide

Building a new wall on the line of junction — the boundary between your property and a neighbour's — is itself a notifiable event under the Party Wall etc. Act 1996. If you want to build a party wall or party fence wall on that line, section 1 requires you to serve written notice on the adjoining owner at least one month before the work starts. If your neighbour consents within 14 days, the wall is built shared — typically half on each owner's land — and the cost is split according to use. If they don't consent, you can still build, but the wall must sit wholly on your own land, at your own cost.

None of that gives your neighbour a veto, but the timing and the paper trail matter a great deal. This guide walks through section 1 step by step, in plain English — what triggers it, what the notice must say, how you should serve it, what happens when your neighbour consents, objects, or simply doesn't answer, and where the traps hide. If you're new to the legislation, our Party Wall Act explained guide is a good starting point, and our definitions page covers the key terms as they come up.

When Does Section 1 Apply?

The phrase "line of junction" is simply a legal term for the boundary line between two pieces of land belonging to different owners — the line you'd see on your title plan at the Land Registry, where your plot ends and your neighbour's begins.

Section 1 applies in two specific situations. First, where the land of two different owners adjoins but is not built on at the line of junction — a classic example is a bare strip of ground between two plots, or an old garden boundary in Ealing where only a low fence has ever stood. Second, where the land is built on at the boundary, but only to the extent of a boundary wall that is either a party fence wall (a garden wall that doesn't form part of either building) or the external wall of a building — and either owner wants to build on that line.

Notice what's not included: if you're building a wall entirely on your own side of the boundary, well inside your garden, the Act doesn't get involved. It's the fact that the wall would be on the line of junction that brings you into the legislation. For a refresher on the different types of wall, our guide on what a party wall actually is is a useful place to start.

One distinction trips people up, so it's worth making it precise. Section 1 is about building a wall where none yet stands on the line, or building alongside an existing boundary feature. If there is already a party fence wall or party wall standing on the boundary and you want to alter, repair, or replace it, that is the other regime — a party structure notice under section 2, with its longer notice period. In practice the dividing line is often just this: replacing an old boundary fence or wall with a new one is usually work to the existing wall under section 2, whereas building a wall where only bare ground or a low chain-link fence stands is a new wall under section 1. When in doubt, it's the sort of call we'll settle for you before you serve anything, because the two notices have different time requirements and the wrong one is an easy way to end up out of order. For the full statutory text and how the three notice triggers fit together, our Party Wall etc. Act 1996 page is the reference to keep to hand.

What Should a Section 1 Notice Actually Contain?

Section 1 does not give a checklist the way the party structure notice does, but a proper notice still has to tell your neighbour, clearly and in writing, what you intend to do. In practice that means five things:

• Who you are and where you are. Your name and your address — the property from which the notice is served. If your neighbour doesn't know you yet, that's the first thing it does for them.
• Who it is addressed to. The name and address of the adjoining owner. If you know it, put it in; if the adjoining plot is empty or the owner isn't easy to pin down, say that and note how you served the notice.
• That you intend to build on the line of junction. Say it plainly — you wish to build a new party wall or party fence wall on the boundary. Vague language like "some boundary work" invites exactly the kind of argument the notice is meant to prevent.
• What the wall will be. Describe it: roughly where it will run, what it will be built of, and how high it will stand. You don't need to attach full technical drawings, but the neighbour should be able to picture the finished wall from your description. This is the description that your neighbour is actually consenting to, so make it match what you'll build.
• When you intend to start. A realistic date on which the building work will begin, at least one month after the date you serve the notice. Set it so you can actually meet it — an impossible date is an opening for a dispute later.

None of this is statutory text you have to copy word for word, but it is the content that keeps a dispute from appearing in the first place. A notice that says "I'm building a wall at the back, mate" is technically a notice; a good one is the difference between a neighbour who replies, "fine, let's share the cost," and one who replies, "I have no idea what you were talking about." Our fixed-price surveyor service prepares a compliant notice with drawings as standard, so that the description your neighbour signs up to is exactly the wall you'll build.

How Do You Serve the Notice, and When Does the Clock Start?

Serving a notice simply means delivering it to the person it is addressed to. The Act doesn't mandate one method over another, but the method determines how cleanly you can prove it happened, so it's worth doing properly. The two reliable routes are personal delivery — hand the notice to your neighbour (or their partner or a member of their household) and get a signature, or have a witness confirm you handed it over — and first-class post to the correct address, keeping your proof of posting and the date. In either case, keep a dated copy of the notice you sent. That copy, plus your proof of service, is the paper trail that matters if a question ever arises about whether, and when, your neighbour was told.

The clock then runs from the date of service, not from when you mentioned the plan over the garden fence. If you serve the notice on a given day, the earliest you can lawfully begin is the corresponding day one month later. And remember the 14-day consent window we've been describing: it also runs from the day the notice is served. So your timeline is really two things starting from the same date — a 14-day period in which your neighbour can consent, and a one-month period before the work may start. Get both dates written down when you serve, because you'll want to be able to point to them later without relying on memory.

Two practical points. First, you serve the notice even if your neighbour is friendly. "That's fine, go ahead" over the garden fence is the most common way people get in trouble: it's a perfectly pleasant conversation and it has no legal weight if the relationship sours and a claim comes through. A friendly neighbour's written consent within the 14-day window is the cleanest possible outcome — no surveyors, no award, just a signed agreement about a shared wall and a cost split — and it's the fastest route through the whole process. The second point is that if your plans change after you've served, or the work slips well beyond the date you gave, the sensible thing is to serve a fresh notice that reflects the new plan rather than rely on the original. A notice that no longer matches what you're doing is a notice a neighbour can argue about.

What Happens If Your Neighbour Consents?

Here's the part that surprises people: consent triggers a sharing arrangement. If, within 14 days of being served your notice, the adjoining owner serves a notice indicating their consent, two things follow automatically:

First, the wall will be built half on the land of each owner — or in such other position as the two of you may agree. So a consent from your neighbour effectively makes the wall a shared party wall, standing half in each garden, rather than a wall on your land that your neighbour simply tolerates.

Second, the cost of building the wall is shared between you, in proportion that has regard to the use each of you makes (or will make) of the wall. If you both use it as a boundary wall for your respective gardens, you're looking at roughly an even split. If it's the party wall for your garden room and your neighbour barely uses it, the proportion shifts accordingly. It's a genuinely sensible piece of drafting, and a good reason to have the conversation about uses — and costs — before you serve anything rather than after.

And if the wall is going to be built on your land alone, there's still a choice to make. Section 1 lets you serve a notice describing a wall that will stand wholly on your own land, at the line of junction. That's the route for when you know — because of how the boundary runs, or how the neighbour's garden sits — that the wall is going to be yours. In that case the 14-day consent window still applies: your neighbour can consent, in which case you build in the position you described (on your land), or they can say nothing, in which case the same position simply becomes the one you're entitled to build at, without a dispute arising. Either way, you build on your own side and you pay for it. Consent doesn't change that for a wall wholly on your land; it just removes any argument about it.

What If Your Neighbour Objects — or Says Nothing at All?

This is where Section 1 is quite different from the rest of the Act, and worth understanding carefully.

Sections 2 and 6 operate on a system of deemed dissent: if your neighbour doesn't respond within 14 days, the law treats them as if they'd objected, and you move into the dispute process with party wall surveyors (explained in detail in our article on what happens when a neighbour ignores your notice). Section 1 does not work that way. If the adjoining owner does not consent within the 14-day window, there's no deemed dissent and no automatic leap into a formal dispute. Instead, the Act simply changes where you can build:

You may only build the wall at your own expense, as an external wall or fence wall, placed wholly on your own land.

In plain English: your neighbour's silence (or objection) doesn't stop your project. It means you can't claim the shared-wall arrangement, so you build the wall on your side of the line of junction, paying the full cost yourself. In a terraced street in Islington where both owners would benefit from a proper shared boundary wall, that outcome is rarely what either party wants — which is why most sensible neighbours use the 14-day window to agree a shared, cost-split wall rather than end up with a wall pressed right up to the boundary on one side only.

The common worry — "will this drag me into a surveyor and a formal award?" — is mostly a misreading of the other sections. Under section 1, a neighbour who objects simply shifts the wall onto your land; it doesn't, by itself, create a dispute that needs a surveyor. A surveyor and a formal award come in only if you and your neighbour can't agree on the details: the exact position of the wall, how the cost should be split, or how much compensation is owed for damage. So an objection is usually not a wall in the road; it's a prompt to put those details on paper before the digger turns up.

What the Notice Actually Means — Three Scenarios

The rules are simple, but they read differently depending on where you live and what you're building. Here are the three situations we see most often.

The low boundary wall in a back garden. Two houses side by side in Ealing with a bare strip between them where a fence once stood. You want to put up a new party fence wall along that line. You serve a Section 1 notice describing the wall — say, a low brick wall a little over head height — one month before you want it built. Your neighbour agrees within the 14-day window. The result: a shared wall standing half on each plot, with the building cost split roughly equally because you both use it as your garden boundary. It's the cleanest case, and the one a friendly neighbourhood usually lands on.

The boundary wall beside a garden room. A home in Islington where a new garden room is being built at the rear, and its boundary wall sits exactly on the line of junction. The garden room is its own set of approvals — it will typically need building regulations approval and, in many cases, planning permission. But the wall itself, because it stands on the line between your land and your neighbour's, is a separate matter governed by Section 1. So you end up with the wall notice and the project approvals running in parallel, and they are genuinely different processes with different decision-makers. Our guide to home extensions and the approvals you need untangles how those sit together; our guide to building control approval for extensions covers what the building side actually involves. Either way, the boundary wall needs its own notice regardless of what the rest of the project involves.

The wall where the gardens don't level out. In older London suburbs it's common for one garden to sit a little lower than its neighbour's. If you're building a wall wholly on your land and it needs a footing that dips below the level of your neighbour's ground to get a stable base, section 1(6) lets you do that during the twelve-month window we cover next. Your neighbour can't stop the footing on that ground; what they can do — and can claim for — is any damage that footing does to their garden, patio, or outbuilding. It's a small point that causes an outsized number of arguments, because the damage shows up where it doesn't look like it's coming from.

What About Projecting Footings Under My Neighbour's Land?

A wall you build wholly on your own land still needs foundations, and if the boundary sits above a dip, a ditch, or a sloping garden (common enough in the older suburbs of North London), the footing will need to project below the level of your neighbour's land to get a stable base. Section 1(6) gives you that right: at any time during a period running from one month after your notice was served until twelve months after that day, you may place such projecting footings and foundations as are necessary for the construction of the wall.

Note that window. If you serve the notice, then sit on it for a year and a half before breaking ground, you lose the statutory right to project footings beneath your neighbour's land. The Act expects the work to actually happen, reasonably soon, once you've given notice. The timing works in your favour only if you act on it, which is another reason to serve the notice close to when you'll actually start rather than months in advance.

Do I Have to Pay for Damage to My Neighbour's Property?

Yes. Whether the wall is built shared or on your land only, section 1(7) is clear that if you build on the line of junction, you must compensate the adjoining owner, and any adjoining occupier, for any damage to their property occasioned by the building of the wall — and by the placing of any projecting footings or foundations under section 1(6).

In practice this means damage to a neighbour's garden, patio, or outbuilding caused by digging the footing trench, or a settlement crack in a boundary feature. It's a good reason to have a schedule of condition in place before the first digger turns over — a documented record of the existing condition of the neighbouring property — so that, if a claim ever arises, there's an agreed baseline rather than a row over what was there beforehand. It's the single most common point of friction in boundary wall works, and the easiest one to get right. The FAQ covers this in more detail, and our guide to surveyor fees explains how these matters cost out in practice.

How Are Disputes Under Section 1 Resolved?

Where a dispute does arise under Section 1 — about whether the notice was properly served, the position of the wall, the proportion of costs, or the amount of compensation — section 1(8) provides that it is to be determined in accordance with section 10 of the Act: the surveyor appointment and award process. If you and your neighbour can't agree who bears what proportion of the cost of a shared wall, for instance, one or more party wall surveyors will be appointed to decide.

How that usually unfolds: one of you serves a notice of appointment of a surveyor, and that surveyor then appoints a second surveyor for the other side (or, if you prefer, the two sides each appoint their own surveyor and those two can jointly agree a third if needed). The surveyors then resolve the points in dispute and issue a written award — the document that, where there's no written consent, is what actually authorises the work and fixes the cost split and any compensation. The surveyors' own costs of that involvement are usually shared under section 11, broadly in proportion to the benefit each side derives from the wall.

The important comfort here is that this is a measured process, not a free-for-all: there's a defined route, a defined document, and a defined basis for who pays what. Getting to a written agreement in the 14-day window skips all of it, which is exactly why we encourage homeowners to use it.

What Mistakes Do Homeowners Make With New Boundary Walls?

After surveying these matters for over fifteen years across Greater London, a few patterns keep recurring, so it's worth listing them out.

The first is assuming a garden wall is "private". If it sits on the line of junction between two owners' land, the Act applies, full stop — regardless of whose land the bricks actually sit on, or who built it. Many of the older boundary walls in London's suburban streets were built in the 19th century under different rules, and their exact position on the boundary is often unclear. If you're not sure where the line of junction actually falls, a boundary survey can settle it before anyone starts digging.

The second is serving a notice that says next to nothing. "Notice to build a wall at the boundary" is a start, but a proper Section 1 notice describes the wall — its height, construction, and position — and gives the start date. A bare notice invites an argument about whether the neighbour was properly told what you were doing, which is exactly the argument the notice was supposed to prevent.

The third is getting the wrong notice for the job — serving a one-month line-of-junction notice for what was actually work to an existing wall, or the reverse. The two have different notice periods, and serving the shorter one for the longer job is how projects end up out of order and exposed.

The fourth, and costliest, mistake is starting work without notice at all. If a neighbour later objects and you have no notice on file, you've exposed yourself to a claim for stopping the work, removing the wall, and compensating for damage — and no surveyor can paper that over afterwards. Cheap, in that case, cost very dear indeed.

Do I Still Need Planning Permission or Building Regulations Approval?

Not necessarily — and it's worth keeping the three regimes straight, because homeowners constantly conflate them. The Party Wall Act is about managing the relationship between neighbouring owners: it doesn't authorise the work itself. Planning permission is a local authority decision about whether the proposed development is acceptable in terms of design, use, and impact. Building regulations approval — administered by your local authority's Building Control department or an approved inspector — covers the structural and technical standards the work must meet.

A modest garden wall up to 2 metres high (1 metre where it bounds a road) is generally permitted development and needs neither — but it can still trigger a Section 1 notice if it sits on the line of junction. A new garden room will typically need building regulation approval and possibly planning permission, and will still need a Section 1 notice for its boundary wall. Three separate regimes, three separate processes, and none of them substitutes for the others. If you're planning a bigger project, our guide to home extensions and the approvals you need untangles the lot, and our guide to building control approval for extensions sets out what that side of the process actually looks like.

How Does Section 1 Sit Against the Other Notice Triggers?

Because the timing is where most mistakes happen, it helps to see the three notice triggers side by side. The table below is a quick reference; each row is a different section of the Act with a different notice period, so mixing them up is the classic error.

If you're doing…	Section	Notice required before you start	If your neighbour doesn't consent
Building a new wall on the line of junction	Section 1	One month	No deemed dissent; you build on your own land at your cost
Work to an existing party wall or party structure (repair, underpin, raise, alter)	Section 2	Two months	Deemed dissent; a dispute arises and surveyors are appointed
Excavation near a neighbour's building	Section 6	One month	Deemed dissent; a dispute arises and surveyors are appointed

The takeaway is the difference in the last column. Sections 2 and 6 are adversarial by design — silence from your neighbour pulls you straight into a formal dispute, because those works carry a genuine risk to the neighbour's building, and the Act builds a whole dispute-and-award machinery around that risk. Section 1 is calmer: there's no existing neighbour's structure at risk, so a wall standing on bare ground doesn't need that machinery, and a non-consenting neighbour simply moves the wall onto your side of the line rather than dragging you into a surveyor. It's a meaningfully easier process, and one more worth understanding precisely, because the two-month party-structure clock and the one-month line-of-junction clock are where well-intentioned homeowners regularly get the dates wrong.

Key Takeaways

Section 1 is the part of the Act that governs building a new wall on the line of junction between your property and a neighbour's. The mechanics are straightforward: a written notice describing the intended wall, served at least one month before the work begins; a 14-day window in which the adjoining owner can consent; and a clear outcome either way. Consent means a shared wall and shared costs in proportion to use. No consent means a wall built wholly on your land, at your cost, with a right to project footings for a further twelve months — and a duty to compensate for any damage to your neighbour's property.

None of it is difficult, but it is unforgiving of sloppiness: get the notice right, get it served properly, get the start date realistic, and keep a record. If you're planning a new boundary wall, garden room, or garage in Greater London, we'd be happy to look at the specifics with you — most Section 1 matters are quick to assess and cheaper to handle early than to argue over later. Call us on 020 8150 3762 or get in touch.

Disclaimer: This article provides general information about Section 1 of the Party Wall etc. Act 1996 and is not intended as legal advice. Every situation is different, and you should seek professional guidance specific to your circumstances. Grey & Associates are party wall surveyors, not solicitors, and cannot provide legal advice. For the full statutory text, see our Party Wall etc. Act 1996 page, which carries the Act section by section.

Grey & Associates are specialist party wall surveyors serving Greater London. Learn more about our team.