Interpretation of Rule 299 Texas Rules of Civil Procedure
"Rule 299 provides that once findings are entered, they "shall form the basis of the judgment upon all grounds of recovery and of defense embraced therein." TEX. R. CIV. P. 299.
Furthermore, "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 . . .." Id.
However, if findings are entered upon one or more of the elements of a theory, then the "omitted, unrequested elements, when supported by evidence" are presumed to have been found in support of the judgment. Id.
As the Amarillo Court of Appeals explained in construing Rule 299:
In other words, one waives (for appellate purposes) a theory of recovery or defense unless the proponent of the theory secures a finding on the theory or an element of the theory.
And, the concept works to the detriment of both appellant and appellee.
For instance, an appellant arguing that the trial court erred in rejecting his defense must make sure that he requested the court to make a finding upon the defense.
If he does not, then the defense is waived.
Similarly, if the appellee fails to request findings upon all his theories of recovery he is precluded from arguing that the court erred in failing to grant relief on the theories it omitted from its findings. Hill v. Hill, 971 S.W.2d 153, 156-57 (Tex. App.--Amarillo 1998, no pet.)(footnote and citations omitted).