Building Control Act 1966

3 Housing and industrial and research premises

(1) There shall be exempt from control under this Act any work done in the construction or alteration of a building which, when constructed or altered, is to be used wholly or mainly for one or more of the following purposes (in this section referred to as " exempted purposes "), that is to say—

(a) as one or more private dwellings;

(b) for carrying on any such process as is mentioned in section 21 of the [1960 c. 18.] Local Employment Act 1960 (definition of " industrial building ");

(c) for carrying on scientific research in the course of a trade or business.

(2) For the purposes of this section there shall be treated as used for exempted purposes—

(a) any part of a building which is used for providing services or facilities reasonably required for the use of the remainder of the building as mentioned in the foregoing subsection; and

(b) any building which is used wholly or mainly for providing services or facilities reasonably required for the use as mentioned in that subsection of a building contiguous or adjacent to it.

(3) For the purposes of this section, a building shall be treated as mainly used for exempted purposes, or for providing such services or facilities as are mentioned in subsection (2)(b) of this section, if (and only if) the gross floor space of the building (ascertained by external measurement) used otherwise than for exempted purposes or, as the case may be, used otherwise than for providing such services or facilities does not exceed twenty per cent. of the gross floor space of the building (ascertained as aforesaid or 20,000 square feet, whichever is the less.

(4) In any case in which work done in the construction or alteration of a building is exempt from control by virtue of subsection (1) of this section there shall also be exempt from control by virtue of that subsection any work done in the construction of any ancillary works required for the building.

(5) The provisions of this section (except subsection (3)) shall, so far as applicable, have effect in relation to works other than buildings as they have effect in relation to buildings.