Work is regarded as commenced where the following applies under regulation 46A:
(2) Construction of a complex building: Foundations completed to support the lowest floor level (but not the other buildings or structures to be supported by those foundations)
(3) Construction or horizontal extension of a building: Sub-surface structure of the building or extension, including all foundations, basement level (if any) and structure of ground floor level is completed.
(4) Any other building work: Where 15% of the proposed work set out in a statement is completed, under regulation 14(1)(f)(vii) or 12(1)(e)(viii) of the Building (Higher Risk Buildings Procedures) Regulations.
Notice under regulation 46A must be provided no more than 5 days after the relevant commenced level has been achieved.