The short answer
Casting a new foundation alongside an existing one and dowelling into it (overpinning) will often not, by itself, require a party structure notice under section 3, because the foundation is not usually the party structure. But that does not mean notice is never required: the whole job must still be checked under sections 1, 2 and 6.
Why it matters
Section 2 gives rights over a party wall or party structure, such as cutting in or cutting away projecting footings, and a foundation is not normally the party structure itself, so dowelling alongside it may fall outside section 2. The important caveat is section 6: an excavation notice is required if the work excavates within 3 metres of an adjoining structure and to a lower depth than its foundations, or within 6 metres where the excavation cuts a plane drawn down at 45 degrees from the underside of those foundations — even if the overpinning itself is not notifiable under section 2. And not needing a notice does not make the work good practice: proper structural design, building control approval where required, and competent construction still matter.
What to do now
- Check the whole project under sections 1, 2 and 6, not just the dowel detail.
- Apply the section 6 distances (3 metres, or 6 metres at 45 degrees) to see whether an excavation notice is required.
- Make sure structural design and building control are in order regardless of any party wall notice.
Common mistakes
- Assuming “no party structure notice” means no notice at all and overlooking section 6.
- Treating the absence of a notice requirement as the absence of risk to the neighbour’s stability.
- Skipping building control or proper design because the Act does not require a notice.
When to call Coburns
If you are overpinning or casting next to an existing foundation, send us the detail and we will confirm whether a section 6 excavation notice is needed.