The Housing Act 2004 - s5
Category 1 hazards: general duty to take enforcement action
(1)If a local housing authority consider that a category 1 hazard exists on any residential premises, they must take the appropriate enforcement action in relation to the hazard.
(2) In subsection (1) “the appropriate enforcement action” means whichever of the following courses of action is indicated by subsection (3) or (4)—
(a) serving an improvement notice under section 11;
(b) making a prohibition order under section 20;
(c) serving a hazard awareness notice under section 28;
(d) taking emergency remedial action under section 40;
(e) making an emergency prohibition order under section 43;
(f) making a demolition order under subsection (1) or (2) of section 265 of the Housing Act 1985 (c. 68);
(g) declaring the area in which the premises concerned are situated to be a clearance area by virtue of section 289(2) of that Act.