Iowa Code § 504.714: Voting requirements.

1. Unless this chapter or the articles or bylaws of a corporation require a greater vote or voting by class, if a quorum is present, the affirmative vote of the votes represented and voting, which affirmative votes also constitute a majority of the required quorum, is the act of the members.

2. A bylaw amendment to increase or decrease the vote required for any member action must be approved by the members.