After the conclusion of any hearing the commission shall make and file its findings and order. The findings of fact shall consist only of such ultimate facts as are necessary to determine the controverted questions presented by the proceeding. Such findings shall be separately stated and numbered, and each thereof shall state briefly and plainly an ultimate fact necessary to determine a controverted question; and there shall be such a finding of fact as to each of the controverted questions presented by the proceeding. The order of the commission shall be based upon said findings of fact, and a copy of the findings of fact and of the order, certified under the seal of the commission, shall be served upon the person against whom it runs, or his attorney, and notice thereof shall be given to the other parties to the proceeding or their attorneys. Said order shall take effect and become operative thirty days after the service thereof, unless otherwise provided. If an order cannot in the judgment of the commission be complied with within thirty days, the commission may grant and prescribe such additional time as in its judgment is reasonably necessary to comply therewith, and may, on application and for good cause shown, extend the time for compliance fixed in its order.