No action of the Board shall be taken on any case until after proper notice has been given and public hearing has been held. The presence of three members shall constitute a quorum and the concurring vote of three members of the Board shall be necessary to reverse or modify any order, requirement, decision or determination of the Commissioner of Buildings or to decide in favor of the appellant any matter upon which the Board is required to pass or to effect any variation. (Ord. 350. Passed 7-6-44.)