(a) The Board of Finance shall also have the care and control of all public buildings not specifically in charge of any other department of the City. They shall appoint such janitors or employ such persons as may be required for the proper care of the buildings, and may prescribe their salaries and define their duties subject to existing collective bargaining agreements.

(b) The Board of Finance may order repairs or enlargements to be made to said buildings, except when the estimated cost of any such repairs or enlargements exceeds $500.00, in such case, prior approval of the Board of Aldermen shall be required.