Party Wall · Process
The Party Wall Act Explained for London Homeowners
Most London extensions and basements engage the Party Wall etc. Act 1996. This guide explains when it applies, what the process involves, and how to plan for it.
The short answer
You need a party wall agreement when your extension builds on or at the boundary, cuts into a shared (party) wall to insert beams, or excavates near a neighbour’s foundations — which covers most London terraced and semi-detached projects and all basements. You must serve notice on the affected neighbours before those works begin.
When the Act applies
The Party Wall etc. Act 1996 applies to a range of common London works: building on or at the boundary, cutting into a party wall to insert beams, and excavating near a neighbour’s foundations — including basement construction. Most terraced and semi-detached house projects engage it in some way.
Notices
Where the Act applies, you must serve notice on the affected neighbours before the relevant works begin, giving the required notice period. Serving clear, accurate notices in good time is important, because the process takes weeks and can delay a project if left late.
Consent or dissent
A neighbour can consent to the works, in which case the process is straightforward, or dissent. If they dissent (or do not respond), a party wall surveyor — or one for each side — is appointed to resolve matters impartially and produce a party wall award before the relevant works start.
The award
The award is a legal document that sets out how and when the works may proceed, records the condition of the neighbouring property beforehand, and provides a framework for resolving any damage. It is produced by the appointed surveyor(s), not by the architect, though accurate drawings underpin a fair award.
How it affects your project
The key is timing: party wall procedures should be started early and planned into the programme, not left until just before works begin. Good architectural drawings and early coordination with a party wall surveyor keep the process smooth and avoid avoidable delays.
Frequently asked questions
Does my architect act as the party wall surveyor?
Can party wall matters delay my project?
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