Public Health Act 1961

6 (1) A building shall be deemed to be erected after the date on which a resolution comes into operation unless its erection was complete before that date.

(2) A building shall be deemed to be erected—

(a) if any part of the building is wholly or partly re-erected when the outer wall of that part has been demolished (otherwise than in consequence of fire or other accident) to within ten feet of the surface of the ground adjoining the lowest storey of that part;

(b) if (not having been originally constructed for human habitation) it is converted into a house ;

(c) if it is converted into a factory, shop or place of public resort;

(d) if it is extended so that the area occupied by the site of the building will (with any previous extension made since the date on which a resolution came into operation in relation to the building) be increased by an area of more than one-eighth or, in the case of a building constructed for agricultural purposes, one-quarter, of that occupied by the site of the building before that date;

and subsection (2) of section ninety of the Public Health Act, 1936 (Which specifies operations which are deemed to be the erection of a building), shall not apply in relation to section twelve or section thirteen of this Act.