What counts as "the line of junction"
The line of junction is simply the boundary between your land and your neighbour's. Section 1 applies if you intend to build a new wall:
- Astride the boundary line itself, or
- Wholly on your own land but up against the boundary.
It doesn't need to be a wall between buildings. A garden wall, a new party fence wall replacing an old timber fence, or a boundary wall enclosing a rear garden can all trigger this section, provided it's a genuinely new wall rather than repair or like-for-like replacement of an existing one.
Why this notice is different
Section 1 has a distinct response mechanism from Section 3 (party structure) or Section 6 (excavation) notices. If you propose to build the wall astride the boundary, your neighbour must actively consent in writing for you to do that — if they don't respond within the notice period, you can't build astride the line without their agreement, though you can still build the wall wholly on your own land.
This is the opposite of the "silence means deemed dissent, triggering a surveyor" pattern that applies to Section 3 and 6 notices. With Section 1, silence on the astride-the-boundary option simply means you build on your own side instead — there's no automatic dispute process forcing a surveyor's involvement unless you specifically want to build astride the line and your neighbour won't agree.
Notice period
A Section 1 notice needs at least one month before work starts — the same period as Section 6, and shorter than the two months required for Section 3 party structure notices. If your boundary wall project also involves excavating close to your neighbour's foundations for the new footings, you may need a Section 6 notice running alongside it — each with its own one-month clock, not a combined period.
Common mistake: assuming repairs don't need notice, when they're actually rebuilds
Replacing a leaning garden wall like-for-like along the same footprint generally isn't notifiable — it's maintenance. But if you're taking the opportunity to raise the height, move the line, or change the foundation design, that shifts it from repair into new-build territory, and Section 1 applies. The distinction is about what you're actually doing, not what you call it.
What this means for your notice
When generating a Section 1 notice, be precise about whether the wall will sit astride the boundary or wholly on your land — this single detail determines what response you actually need from your neighbour and what happens if they don't reply. As always, the accuracy of what you enter about the wall's position is what makes the notice work correctly; the platform can't infer intent you haven't stated.