Every London extension that touches a shared wall, and many that simply dig new foundations near one, triggers the Party Wall Act 1996. Get it wrong and your neighbour can stop your project.
When you need a notice
You need to serve a Party Wall Notice if you plan to cut into a shared wall for new beams or pockets, build a new wall on or up to the line of junction with a neighbour, or excavate within 3 m of a neighbour structure to a depth below their foundations.
How long it takes
Notices must be served at least two months before work starts. If a neighbour dissents, both parties appoint surveyors who agree a Party Wall Award. That can take another four to eight weeks.
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