The Board of Finance may cause such repairs or enlargements to be made to said buildings from time to time as the interests of the City may require; provided, however, that when the estimated cost of any such repairs or enlargements exceeds the amount of money appropriated by the City Council to the public buildings account in any fiscal year, they shall make report thereon to the City Council for their approval before any expenditure shall be made for such purpose, and shall in April and October of each year report the condition of said buildings to the City Council.