Party Wall Agreement Cost Guide 2026
If your extension is near a shared boundary, you may need a party wall agreement under the Party Wall Act 1996. This is separate from planning permission and can be an unwelcome surprise cost.
Cost breakdown
When you need a party wall agreement
You need to serve a Party Wall Notice if: building on or at the boundary, cutting into a party wall, or excavating within 3m of a neighbouring building (or 6m if your foundations go deeper than theirs). Most terraced and semi-detached extensions trigger party wall requirements.
The cost
If your neighbour consents (no surveyor needed): £0. If your neighbour dissents (surveyors required): £700–£1,500 per neighbour. You (the building owner) typically pay for both your surveyor and your neighbour's surveyor. With two neighbours (typical terrace), costs can reach £3,000.
| Scenario | Typical Cost |
|---|---|
| Neighbour consents in writing | £0 |
| One neighbour dissents (two surveyors) | £700–£1,500 |
| Two neighbours dissent | £1,400–£3,000 |
| Agreed surveyor (one surveyor for both) | £500–£1,000 |
| Schedule of condition survey | £200–£400 per property |
Prices based on Dorset rates, 2026
Frequently asked questions
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