Party wall procedure catches people out because it runs on its own timetable, independent of planning and building control. On terraced and semi-detached properties it is often the item that sets your earliest possible start date.
Work that commonly triggers it
Cutting into a shared wall to bear a new steel, removing chimney breasts on a party wall, and excavating foundations close to a neighbouring structure are the usual triggers on domestic jobs.
Notice periods
Different types of work carry different notice periods, and the clock only starts once a valid notice is served. Serving early costs nothing and protects your programme.
Consent or dissent
A neighbour can consent in writing, which ends the process, or dissent, which leads to surveyors and an award. Neither is a disaster; being surprised by it mid-build is.
Record the condition first
A schedule of condition of the neighbouring property before work starts protects both sides if a dispute arises about cracking or damage later.