20.—(1) No part of any numbered work in Schedule 1 (authorised development) is to commence until written details of all proposed permanent and temporary fences, walls and other means of enclosure relevant to that numbered work have been submitted to and approved in writing by the relevant planning authority.
(2) The approved temporary fencing or enclosure must be erected in accordance with the details approved under sub-paragraph (1) and must be retained throughout the construction of the relevant numbered work.
(3) Any temporary fencing must be removed on completion of the authorised development.
(4) The approved permanent fencing or enclosure must be erected in accordance with the details approved under sub-paragraph (1) prior to the relevant part of the authorised development being opened to the public for use.