How long does a party wall agreement last? The key deadline is at the start: works authorised by a notice must begin within 12 months of the notice being served (and be prosecuted with due diligence), or the notice lapses and you must re-serve. The award itself does not “expire” once works have properly begun.
The 12-month rule in practice
Serve notice too early and your build programme slips past a year — a common London story with basement projects — and you are back to square one: new notice, fresh response period, possibly new surveyor fees. Time notices to land 2–3 months before a realistic start date. Our guide on when to serve notices covers the sequencing.
Does a party wall award expire?
Once works start in time, the award governs them to completion — including access rules, working hours and making good. Its damage provisions and the schedule of condition continue to protect both owners after completion, and awards are routinely produced years later when properties are sold.
Changing plans mid-project
If the design changes materially from what the award authorised, an addendum award (or fresh notice for new notifiable work) is needed — building beyond the award is treated like building with no agreement at all: see is a party wall agreement legally required?
Check your dates before you commit
Send us your notice or award and programme — we will confirm in one call whether you are still covered. 0204 579 8270 or ask us free.
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