320.42—Decision of Board.
The decision of the Board, whether on an appeal to the Board from a decision of a hearings officer, or after submission of a report by a hearings officer, shall be made upon the basis of the record established in accordance with the foregoing sections. Notice of such decision, together with the Board's findings of fact and conclusions of law in connection therewith, shall, within 15 days from the date on which the decision is made, be mailed to the parties at the latest addresses furnished by them. Subject only to judicial review in accordance with § 320.45, the decision of the Board shall be final and conclusive for all purposes:
(b)
With respect to other initial determinations, irrespective of whether they have been appealed, which involve the same parties and which were based on the same issue or issues determined in the decision of the Board. In a case in which there has been a hearings officer's report, in an appeal involving employee status or the creditability of compensation, the decision of the Board on all issues determined in such decision shall be final and conclusively establish all rights and obligations, arising under the Act, of every party notified as hereinabove provided of his or her right to participate in the proceedings.