The Board, when so appealed to and after a hearing, may vary the application of any provisions of the code to any particular case, when in its opinion, the enforcement thereof would do manifest injustice, and would be contrary to the spirit and purpose of the code or public interest, or when in its opinion, the interpretation of the Building Official should be modified or reversed. A decision of the Board to vary the application of any provision of the code or to modify an order of the Building Official shall specify in what manner such variation or modification is made, the conditions upon which it is made and the reason therefor.
('90 Code, § 7-46.20)