(a) If the time within which an award is rendered has not been fixed in the arbitration agreement, the arbitrator or arbitrators or umpire shall render the award within thirty days from the date the hearing or hearings are completed, or, if the parties are to submit additional material after the hearing or hearings, thirty days from the date fixed by the arbitrator or arbitrators or umpire for the receipt of the material. An award made after that time shall have no legal effect unless the parties expressly extend the time in which the award may be made by an extension or ratification in writing.

(b) The award shall be in writing and signed by the arbitrator or arbitrators, or a majority of them, or by the umpire. Written notice of the award shall be given to each party.