An appeal may be taken to the ZBA by any person, firm or corporation, or by any officer, department, board or bureau affected by a decision of the Building Department or the Planning Commission. A request to be heard by the Board of Appeals shall be filed within 21 days from the date of the event for which the appeal is being taken. The appeal shall be filed with the Building Director and with the ZBA. A notice of appeal shall specify the reason or grounds for the appeal. The Building Director shall forthwith transmit to the Board all of the papers constituting the record upon which the action appealed from was taken. An appeal shall stay all proceedings in furtherance of the action appealed from unless the Zoning Administrator certifies to the ZBA, after notice of appeal has been filed with him, that by reason of facts stated in the certificate, a stay would, in his opinion, cause imminent peril to life or property, in which case the proceedings shall not be stayed, otherwise than by a restraining order, which may be granted by a court of record. The ZBA shall select a reasonable time and place for the hearing of the appeal and shall give due notice thereof to the parties and shall render a decision on the appeal without unreasonable delay. Any person may appear and testify at the hearing, either in person or by a duly authorized agent or attorney.