Building a wall right up to the boundary? Get the notice sorted first

A new brick house being built on the boundary line with its shared wall highlighted, a surveyor and a notice beside it

For homeowners in England and Wales building a garage, side extension or boundary wall right up to the property line. Compare quotes from party wall surveyors who can prepare the notice.

The line of junction is the boundary between your land and your neighbour’s. If you are building a new wall on it, or right up to it, where no wall stood before, the Party Wall etc. Act 1996 can ask for a notice at least one month before you start. It covers the side wall of a garage or extension built up to the boundary, and a garden wall on the line. A wall that straddles the boundary needs your neighbour’s agreement. Without it, the wall goes wholly on your own land. A structural engineer should design the footings, and a party wall surveyor can prepare the notice.

How a professional can help

Deciding where the wall can go: A surveyor explains your options: building across the boundary with your neighbour’s agreement, or wholly on your own land. Where the true boundary lies matters, and the Act doesn’t settle boundary disputes.
Footings that spread beneath next door: A wall on your own land can need footings wider than the wall, projecting under the neighbour’s ground. The Act allows ordinary projecting footings, but special foundations such as reinforced concrete under their land need the neighbour’s written consent, so your surveyor and engineer should agree the detail early.
Preparing the line of junction notice: The notice describes the new wall, where it will stand in relation to the boundary, the foundations and how it will be built, with plans attached. It goes to every owner of the adjoining land with the date recorded.
Asking to build across the boundary: If you want the wall to straddle the boundary, your neighbour must agree. A surveyor can help you explain what is proposed so the neighbour feels comfortable, and makes sure any agreement is recorded in writing.
Protecting the ground next door: Digging footings right beside a boundary can disturb fences, paving, drains and planting. Surveyors can agree how the neighbour’s side is protected and how anything damaged will be made good.
Fitting the notice into the wider job: A boundary wall for an extension may come with work to an existing party wall or deeper digging. Your surveyor checks whether further notices are needed so that they are served together and on time.

Is this right for you?

You’re building a side extension or garage whose outer wall will sit right on the boundary.
You’re putting up a new garden or boundary wall on the line between two properties.
You’re building a new house or garage on a plot where nothing stands on the boundary yet, so its wall will sit on or beside the line.
You’re not certain where your boundary lies and want to understand the limits of the Act before you build.
You want to ask your neighbour’s agreement to build across the boundary.

How the project usually runs

Fix the position of the wall: Your designer and engineer settle where the wall will stand and how deep the footings go, and the surveyor checks the boundary evidence against the drawings.
Draft the line of junction notice: The notice describes the wall, its position and the foundations, with plans, and gives a start date at least one month ahead. If you want the wall to straddle the boundary, it says so.
Serve it on the adjoining owners: It is delivered to every owner of the adjoining land, by hand or post, and the date is logged. The neighbour then has 14 days to reply.
Agreement, or the wall goes on your land: A neighbour who agrees to a wall across the boundary confirms in writing. If they don’t agree, the wall goes wholly on your own land, and a surveyor can advise on what else the Act requires.
Build, then check next door: Groundworks follow the engineer’s design and the wall is built to the agreed position. Afterwards, the neighbour’s side can be inspected against the earlier record and any damage dealt with.

What affects the cost

Whether the wall is a short garden wall or the full side wall of a garage or extension, which changes how much needs describing.
Whether the neighbour agrees to the wall straddling the boundary or it goes wholly on your own land.
Whether deeper or special foundations project under the neighbour’s land, which calls for more technical review and, for special foundations, the neighbour’s written consent.
How much of the neighbour’s side needs recording, including fences, paving, drains and outbuildings.
Whether the same project also involves work to an existing shared wall or deep digging, which needs further notices.

Building on the boundary: other rules to check

New boundary walls fall under the Party Wall etc. Act 1996 in England and Wales. Scotland and Northern Ireland follow different rules, and surveyors across the UK can explain what applies to you.
A line of junction notice doesn’t decide where the legal boundary is. If you and your neighbour disagree about that, it is a separate matter needing boundary advice.
Walls close to a boundary can have fire resistance and opening requirements under Building Regulations, and may need planning permission. The Act covers neither.
Foundations should be designed by a structural engineer, who will consider the ground, any trees and the drains nearby.

Questions people ask

Do I need a line of junction notice if I build entirely on my own land?

It depends on where the wall sits. A wall built well inside your own land is not at the line of junction, although deep foundations near a neighbour’s building can still need an excavation notice. A wall right up to the boundary is different, especially if its footings will extend under next door’s ground. A party wall surveyor can confirm from your drawings.

Can my neighbour stop me building the wall on the boundary?

They can decline to agree to a wall straddling the boundary, in which case the wall goes wholly on your own land. Whether you can build up to the line also depends on planning, Building Regulations and the footings, so ask a party wall surveyor early rather than after the design is fixed.

Can I go onto next door’s land to build the wall?

Building right on a boundary often needs a little working space on the other side. The Act gives a building owner a right to enter neighbouring land for work it covers, normally after giving notice, and must compensate for any damage it causes. It is far smoother to agree dates and access with your neighbour first.

What if I’m not sure where the boundary is?

Find out before you serve the notice. The Act deals with building at the boundary, not with deciding where it is. Deeds, a title plan, existing fences and a boundary survey can all help, and if you and your neighbour disagree, a specialist adviser can help you settle it.

Does the wall need foundations that go under my neighbour’s land?

Sometimes. A wall built right on the boundary can need footings wider than the wall, and these may extend beneath next door’s land. The Act allows ordinary footings to project in this way. Reinforced concrete (special) foundations under their land need the neighbour’s written consent, and deeper foundations need particular care, so your structural engineer and surveyor should agree the approach before the notice goes out.

Available across the UK

Party wall surveyors cover the whole of the UK. The Party Wall etc. Act 1996 applies in England and Wales; Scotland and Northern Ireland have different rules, and a professional can tell you what applies to your property.