The short answer
Yes. An adjoining owner can object to mass concrete underpinning where it causes real prejudice, particularly if it projects beyond the face of the party wall or restricts future development options. The question is not whether mass concrete is a common method, but whether the design is necessary, proportionate and fair to both properties.
Why it matters
Underpinning that extends beyond the wall line can reduce the adjoining owner’s future basement potential, create a permanent below-ground obstruction, complicate future structural works, raise boundary and encroachment issues, and affect long-term value and flexibility — real concerns, not objections for their own sake. Surveyors must act impartially: they are not there to approve the building owner’s preferred method just because it is cheaper or convenient, but to consider whether the work can be authorised under the Act and what safeguards or design changes protect both owners. Note that mass concrete is not usually a special foundation merely because it is concrete; special foundations are a separate concept generally involving reinforced concrete or reinforced masonry. Even where consent to special foundations is not required, surveyors must still consider whether the underpinning is reasonable and avoids avoidable prejudice.
What to do now
- As an adjoining owner, object on substance — projection beyond the wall or loss of future basement potential — not on principle.
- As a building owner, look at compromises: extending the wall downwards at or near its existing thickness, a narrower or more carefully designed foundation detail, and limiting projection to what is structurally necessary.
- Record the agreed arrangement clearly in the award and preserve future development options as far as reasonably possible.
Common mistakes
- Assuming mass concrete is automatically acceptable because it is a common method.
- Treating “not a special foundation” as meaning the design cannot be questioned.
- Allowing underpinning to project beyond the wall without considering the neighbour’s future use.
When to call Coburns
If mass concrete underpinning is proposed near your boundary, on either side, send us the drawings and we will advise whether it is reasonable and what safeguards belong in the award.