Works
How deep foundations can go
The excavation tests use depth measured against the neighbour’s foundations and the distance from their building. Both numbers come from a drawing, not from a rule of thumb in a blog.
This is general information for England and Wales. It is not a decision on your building. Status: pending project-specific review by a qualified Party Wall professional. House-style review 27 September 2026.
What to ask your engineer for
A section showing your proposed underside of foundation, the boundary, and the neighbour’s foundation if it is known. If the neighbour’s depth is unknown, say so. Surveyors often have to work with that uncertainty. They do not invent a depth to make the notice shorter.
A Party Wall Notice does not replace planning permission, building regulations approval, leaseholder or freeholder consent, or structural advice. This platform does not provide legal advice and does not issue Awards.