This section applies where—
on any day ("the relevant day") an initial notice is given in respect of any work, and
the initial notice is accepted.
Where the work relates to one building and is not commenced within 3 years from the end of the relevant day—
the initial notice ceases to be in force, and
if a plans certificate relating to the work (or any part of it) has been accepted, the relevant provisions have effect as if the certificate had not been given (or accepted).
Where the work relates to more than one building, and the work in relation to one or more of the buildings ("the relevant work") is not commenced within 3 years from the end of the relevant day—
the initial notice ceases to be in force so far as it relates to the relevant work, and
if a plans certificate relating to the relevant work (or any part of it) has been accepted, the relevant provisions have effect as if, as regards the relevant work, the certificate had not been given (or accepted).
For the purposes of subsection (3)(b) it does not matter whether the plans certificate also relates to work other than the relevant work.
In this section "the relevant provisions" has the meaning given by section 32.
Building regulations may make provision about when work, or work relating to a building, is to be regarded as commenced for the purposes of this section.