70 ILCS 1805/26

Regular meetings of the Board shall be held at least once in each calendar month, the time and place of meetings to be fixed by the Board. All members of the Board must be present in person to constitute a quorum for the transaction of business. All action of the Board shall be by ordinance or resolution. The affirmative vote of at least 2 members shall be necessary for the adoption of any ordinance or resolution. All ordinances and resolutions before taking effect shall be approved and signed by the chairman of the Board.