Three questions decide which notices you need
- Is any new wall going on the boundary? Then you need a Section 1 notice, one month ahead.
- Will you cut into or connect with an existing shared wall? Then you need a Section 3 notice, two months ahead.
- Will the foundations be deeper than your neighbour’s, within 3 or 6 metres of their building? Then you need a Section 6 notice, one month ahead.
You can answer yes to more than one. We serve the notices together, so your neighbour receives one clear package.
Common extensions and what they trigger
| Extension | Notices often needed |
|---|---|
| Rear extension set in from the boundary, with foundations deeper than the neighbour’s | Section 6 |
| Rear extension built up to the boundary | Section 1, and often Section 6 |
| Rear extension that joins or cuts into the existing party wall | Section 3, and often Section 6 |
| Side return infill in a terrace, built along the boundary wall | Often Section 3 and Section 6, because the wall is shared or is raised |
| Side extension on a wide plot, set away from the neighbour | Section 6 if foundations are deep and close enough |
| Garden room or annexe near the boundary | Section 6 only if it has deep foundations near their structure |
These are patterns, not rules. The drawings decide.
Foundations: the point most owners miss
Modern extension foundations are commonly a metre or more deep, and building control can require them deeper. Older or simpler neighbouring buildings often have shallower foundations. So an extension that looks nowhere near the neighbour can still dig below the base of their foundations, which is exactly what Section 6 exists to catch.
If you are not sure how deep your neighbour’s foundations are, a trial hole will show you. Often it is safer to serve the notice anyway. The rules apply to any structure of the neighbour’s, such as a garage, outbuilding or masonry garden wall, not only their house. Read Section 6 notices for the two tests and a diagram.
The side return in a terrace
A side return extension usually runs along the boundary wall between two terraced houses. That wall may be a party wall, a party fence wall or the flank wall of a neighbour’s own extension. Raising it, cutting into it or building against it can need a notice, and the new foundations beside the neighbour’s house often need a Section 6 notice. This is where we see the most mistakes, so get the drawings checked before you serve anything.
Where the new roof meets a neighbour’s wall
A new roof that butts up to a neighbour’s wall needs a weathertight junction, and that usually means cutting a flashing into their wall. The Act allows it, provided all damage is made good, but a Section 3 notice must come first. Where part of the neighbour’s building, such as eaves or a gutter, overhangs your land or rests on the party wall, the Act also lets you cut it away to the extent necessary for a new vertical wall, and requires you to make good any damage. See roofing work and the Act for the full list of roof jobs that need a notice.
Timing
Serve the notices when your drawings are settled and before you commit a start date to your builder. A Section 3 notice needs two months, and the award comes on top if your neighbour dissents or says nothing. Foundations are the first thing built, so the party wall process holds up the whole programme if it is left late.
Planning is separate
Planning permission, prior approval for a larger home extension and building regulations approval are separate from the Act. None replaces a notice and a notice replaces none of them.
What it costs
A notice is £70, a schedule of condition of your neighbour’s property is £350 and an award as agreed surveyor is from £600, with no VAT. See how our fees work. Send us the drawings or call 0800 999 1947 and we will tell you which notices apply.
Extension questions
My extension stays 2 metres from the boundary. Do I still need a notice?
Possibly. The 3 and 6 metre distances are measured from your neighbour’s building or structure, not from the boundary. If your new foundations will be deeper than theirs and within 3 metres of their house, garage or other structure, or cut the 45 degree line within 6 metres, you need a Section 6 notice.
What if my foundations are shallower than my neighbour’s?
A Section 6 notice is triggered by digging deeper than the base of their foundations (within 3 metres) or cutting the 45 degree line (within 6 metres). If neither is true, you do not need one for the excavation, though other parts of the work may still need a notice.
Do I need a notice for a single-storey extension?
Height is not the test. What matters is the position of the new walls, whether you cut into a shared wall and how deep the foundations go. A single-storey extension on a deep foundation beside a neighbour can need a notice, and a tall one set well away may not.
Is neighbour consultation under planning the same as a party wall notice?
No. Some larger extensions require the council to consult neighbours as part of planning. That is a planning process. A party wall notice is separate and has to be served by you under the Act.
Do I need a party wall notice for a conservatory or orangery?
It depends on the same three questions as any extension, not on the word conservatory. A conservatory built up to the boundary, tied into a shared wall or dug in deeper than your neighbour’s foundations can need a notice. One built well away from the boundary on shallow foundations often does not, but your neighbour’s foundations may be shallower still, so check before you assume.