If—
serving an improvement notice under this section in respect of the hazard is a course of action available to the authority in relation to the hazard for the purposes of section 5 (category 1 hazards: general duty to take enforcement action).
An improvement notice under this section is a notice requiring the person on whom it is served to take such remedial action in respect of the hazard concerned as is specified in the notice in accordance with subsections (3) to (5) and section 13.
The notice may not, by virtue of subsection (3)(b) or (c), require any remedial action to be taken in relation to any part of the building or its external common parts that is not included in any residential premises on which the hazard exists, unless the authority are satisfied—
The remedial action required to be taken by the notice —
An improvement notice under this section may relate to more than one category 1 hazard on the same premises or in the same building containing one or more flats.
The operation of an improvement notice under this section may be suspended in accordance with section 14.
In this Part "remedial action", in relation to a hazard, means action (whether in the form of carrying out works or otherwise) which, in the opinion of the local housing authority, will remove or reduce the hazard.