If your project involves digging, underpinning or new structural supports near a boundary, you’ll run into the term special foundations. Getting this right matters: surveyors cannot authorise special foundations on or under a neighbour’s land without the neighbour’s express written consent. Here’s a plain-English guide.
The legal definition (Section 20)
Under the Act, “special foundations” means:
foundations in which an assemblage of beams or rods is employed for the purpose of distributing any load.
In practice, that means reinforced foundations—typically reinforced concrete (rebar cages, meshes, rods, ground beams, rafts). By contrast, mass (plain) concrete without reinforcement is not a special foundation.
Why the definition matters
- Projection under the boundary:
If you’re building up to the boundary (a Section 1(5) “line of junction” scenario), the Act gives a right to project ordinary footings onto/under the neighbour’s land if necessary. But not special foundations. Those need the neighbour’s consent—a surveyor cannot grant it for you. - Astride the boundary (Section 1(2)):
If the neighbour consents to a shared wall astride the line, you may still need separate, explicit consent if the design uses special foundations under their land. - Awards can’t force special foundations under next-door:
Even when surveyors are appointed and an Award is made, they cannot compel special foundations to extend beneath the adjoining owner’s land without that owner’s written consent.
Common works—are they “special” or not?
| Work type | Typical foundation detail | Special foundation? | Notes |
|---|---|---|---|
| Basement construction | Reinforced slab/raft + reinforced retaining walls/ground beams | Yes | Expect rebar throughout; you cannot extend it under neighbour’s land without consent. |
| Underpinning | Mass concrete pins | No | Mass concrete pins (no rebar) are ordinary; may be used where projection is needed. |
| Underpinning | Reinforced pins/needles/ground beams | Yes | Needs consent if any part projects under neighbour’s land. |
| Rear/side extension | Trench fill (plain concrete) wholly on your land | No | Usually fine if it doesn’t project. |
| Piled foundations | Reinforced piles + reinforced ground beam | Yes | Special; keep entirely on your land unless neighbour consents. |
| Lightwell/deep excavations | Reinforced capping beam/raft | Yes | Treat as special; design to avoid crossing the boundary unless agreed. |
Typical design choices we see
- To avoid needing consent: Engineers will often specify plain (mass) concrete where a footing needs to project under the neighbour’s land.
- Where reinforcement is essential: Keep all reinforced elements wholly on your land or seek the neighbour’s written consent up-front.
Practical tips to stay compliant (and on programme)
- Ask early: Get your engineer to confirm whether any foundation element is reinforced and projects under the boundary.
- Map it to the Act: If it’s special and crosses the boundary, you’ll need the adjoining owner’s consent—not just an Award.
- Offer alternatives: If consent isn’t forthcoming, be ready with an ordinary (mass) concrete alternative where safe/viable.
- Show the drawings: Clear sections and details reduce objections—and speed up surveyor agreement.
Simple Survey — Clear Advice, Valid Notices, Sensible Fees
Our simple cost chart
- Party Wall Notice service: £25 per adjoining ownership (multi-notice bundles discounted)
- Act administration as Agreed Surveyor (single surveyor): typically £300 fixed-fee (depends on complexity and number of notices/owners)
- Two-surveyor route (we act for the Building Owner): fixed-fee proposals from £325 for our side (we work to keep your neighbour’s surveyor’s hourly fees reasonable and contained)
Ready to sanity-check your foundation design?
Send us your address and structural/architectural sections. We’ll confirm whether your scheme introduces special foundations, explain your consent options, and set out the most time- and cost-effective route to a compliant Party Wall Award.
Email: team@simplesurvey.co.uk
Get clarity now—so you can build with confidence later.