The Chief Building Official may issue a permit for the construction of foundations or any other part of a building or structure before the entire drawings and specifications for the whole building have been submitted, provided adequate information and detailed statements have been filed to demonstrate that an unjustifiable hardship will be entailed by the applicant if he is required to delay initiation of said work until completion and approval of the drawings and specifications together with such other data as may be necessary to demonstrate that the work will comply with all the pertinent requirements of this Building Code. The holder of such permit for the foundations or other part of the building or structure shall proceed at his own risk with the building operation and without assurance that a permit for the entire structure will be granted.
(‘74 Code, § 150.33)