Why detached houses feel exempt
The best-known part of the Act deals with shared walls, and a detached house does not have one. So owners reasonably assume that the Act does not apply to them. In many projects, that is right. But two parts of the Act do not depend on a shared wall.
Two ways it still applies
1. Digging near a neighbour’s building (Section 6). If you excavate close to a neighbour’s building or structure, and deeper than the base of its foundations, you need to serve a Section 6 notice. The two tests are:
- within 3 metres of their building, and deeper than the base of its foundations, or
- within 6 metres of it, where the excavation cuts a line drawn downwards at 45 degrees from the base of its foundations.
The distances are measured from the neighbour’s building or structure, not from the boundary. On many suburban plots, houses stand only a few metres apart, so a detached house is often within 6 metres of its neighbour’s.
2. Building on the boundary (Section 1). If you build a new wall on the line between your land and your neighbour’s, you need a Section 1 notice one month ahead. This catches new masonry boundary walls and extensions built right up to the boundary.
An existing masonry garden wall on the boundary is a party fence wall. Raising or rebuilding it brings in the other parts of the Act too. See fences and garden walls.
Detached house projects and notices
| Project | Notice likely? |
|---|---|
| Loft conversion or garage conversion with no digging | Usually not |
| Rear extension far from the neighbour, say more than 6 metres | Usually not |
| Side extension with deep foundations close to the neighbour’s house | Section 6 may apply, depending on depth and distance |
| Basement or deep excavation within 6 metres of a neighbour’s building | Often Section 6 |
| New masonry boundary wall | Section 1 |
| Raising an existing masonry garden wall on the boundary | Section 3 |
| Lift pit, swimming pool or deep drains close to a neighbour’s building | Section 6 may apply |
| Garden room on a shallow base | Usually not |
These are patterns, not rules. The depths and the distances decide.
How to find out
- Measure the distance from your proposed excavation to your neighbour’s nearest building or structure, including garages and outbuildings.
- Find out how deep their foundations are. A trial hole is the reliable way. Older and simpler buildings often have shallow foundations, so the answer is often “shallower than yours”.
- Check your own depth. Extension foundations are commonly a metre or more, and building control can require more.
- If in doubt, serve the notice. It is much cheaper than an argument, and it gives you a schedule of condition if the neighbour dissents.
Planning and building regulations
These are separate from the Act. Having planning permission does not remove the need for a notice, and serving a notice does not give you planning permission.
Talk to us
Send us the drawings, or call 0800 999 1947. The first call is free, and we will tell you whether the Act applies and what it would cost. Our notices are a fixed £70, with no VAT.
Questions about detached houses
I own a detached house and my neighbour’s house is 5 metres away. Do I need a notice for an extension?
Only if the excavation meets one of the two tests. Within 3 metres of their building and deeper than their foundations, or within 6 metres and cutting the 45 degree line down from the base of their foundations. At 5 metres, only the second test is in play. Send us the drawings and we will tell you.
Does a loft conversion on a detached house need a notice?
Usually not, because there is no shared wall to cut into. Planning and building regulations still apply.
Does the neighbour’s garage count?
Yes. The excavation rules apply to any building or structure of the adjoining owner, not just the house.