When findings of fact are sent by the trial court they must form the basis of the judgment upon all grounds of recovery and of defense embraced therein. The judgment may not be supported upon appeal by a presumed finding upon any ground of recovery or defense, no element of which has been included in the findings of fact; but when one or more elements thereof have been found by the trial court, omitted unrequested elements, when supported by evidence, will be supplied by presumption in support of the judgment. Refusal of the court to make a finding requested is reviewable on appeal.