4.—(1) These regulations shall not apply to building work for the purposes of national security.
(2) Subject to paragraph (3), these regulations shall not apply to—
(a)building work in connection with any buildings belonging to any statutory undertakers and held or used by them for the purposes of their undertaking provided that this exemption shall not extend to dwellings or to buildings used as offices, shops, showrooms or passenger stations for air, road, rail or sea travel;
(b)the erection of any exempted building (including the provision of any service or fitting solely in connection therewith); and
(c)the alteration of or extension to or the provision of any service or fitting solely in connection with an exempted building, if after the carrying out of that work the building remains an exempted building.
(3) The building work in paragraph (2) shall not create a new or greater contravention of any relevant requirement of these regulations in any part of a building or in any other building to which these regulations apply.
(4) In determining for the purposes of paragraph (3) whether any building work would cause a new or greater contravention of any of these regulations, sub-paragraphs (a) and (b) of regulation 7(3) shall apply.
(5) For the purposes of paragraph (3) and Schedule 2—
(a)a building shall not be regarded as attached to another building solely by virtue of it being attached to a fence, garden wall or similar structure; and
(b)“building to which these regulations apply” means a building which, if it were being newly erected, would be subject to the control of any regulation in Parts C to L and Parts R and V.