This guide explains how long Party Wall Notices remain effective, the minimum lead-in periods before works can start, and how to calculate the time limits set by the Party Wall etc. Act 1996 (“the Act”).
1) Minimum notice periods (before works may begin)
The Act sets different minimum lead times depending on the work:
- Party Structure Notice (s.3 / s.2 works): at least 2 months before the proposed start date.
- Line of Junction Notice (s.1) and Adjacent Excavation Notice (s.6): at least 1 month before the proposed start date.
These “one month” and “two months” periods are calendar months, not fixed day counts.
2) How long is a served Notice “valid”?
Per s.3(2)(b) (mirrored in s.1 and s.6), a Notice ceases to have effect if:
- the notified works have not begun within 12 months of the date the Notice was served; or
- the works are not prosecuted with due diligence once begun.
Key points:
- The 12-month clock starts on the day of service of the relevant Notice.
- You must start (not necessarily finish) the notifiable works within that 12-month window.
- After starting, you must proceed with due diligence (no unreasonable gaps).
Consent vs Award doesn’t change the 12-month rule
- If the Adjoining Owner consents, the Building Owner still has 12 months from Notice service to start.
- If the Adjoining Owner dissents and a Party Wall Award is made, the statutory 12-month limit still runs from the Notice date, not the Award date.
- An Award may include additional programme constraints, but it doesn’t reset the Act’s 12-month statutory window.
- If the 12 months expires before works start, the solution is usually to re-serve a fresh Notice.
3) Practical scenario
You served a compliant Notice and then paused the project for funding reasons. Six months later, with no design change, you want to proceed.
- The original Notice is still within 12 months, so—assuming service was valid and the proposal hasn’t changed—it can still be relied upon for the Adjoining Owner to respond (consent/dissent).
- If design has changed materially, serve a new Notice reflecting the revised works.
4) Calculating calendar months (simple method)
Don’t count days. Keep the same day-of-month and add the months.
- Example (2 months): 15 January → 15 March
- If the target month lacks that day (e.g., 31 January + 1 month), use the last day of the target month.
5) Shorter response periods: 14 days & 10 days
- The Act uses days, which are calendar days (weekends and public holidays count).
- Typical flow:
- 14 days for the Adjoining Owner to reply to a Notice.
- If no reply, a 10-day request to appoint a surveyor under s.10(4) can be issued.
- If there’s still no response after the 10 days, the Building Owner’s surveyor may appoint a surveyor on behalf of the Adjoining Owner so the Award can be made.
At-a-glance: Do’s & Don’ts
- Do serve the correct Notice with the statutory lead-in (2 months for party structure; 1 month for line of junction/excavations).
- Do start notifiable works within 12 months of service of the Notice.
- Don’t assume the Award gives you a fresh 12 months—the Notice controls the statutory window.
- Do re-serve a new Notice if the 12 months lapses or the design materially changes.
- Do plan for the 14-day and 10-day response steps when programming your project.
Want your dates and documents checked?
Email team@simplesurvey.co.uk. Simple Survey are the lowest-cost party wall surveyors across England & Wales—we’ll keep you compliant, on time, and dispute-ready.