Gilmore

*758 Opinion

1. Introduction

Appellant Hilary Gilmore, formerly Hilary Biallas (Mother), appeals from a postjudgment order transferring physical custody of a minor child from her to respondent Mark Lee Biallas (Father). We hold that the trial court incorrectly made a de novo determination on the issue of custody, and therefore the order must be reversed and the case remanded for a determination as to whether changed circumstances show that the best interests of the child would be served by a change in custody from Mother to Father..

2. Facts

Mother and Father were married in 1988 and separated on September 15, 1990. Their only child, a son, was bom on April 13, 1990. The judgment of dissolution awarded joint legal custody of the son to the parents. The judgment also awarded “primary physical custody” of the son to Mother and gave Father reasonable visitation periods, including from Sunday morning to Monday morning and from Wednesday evening until Thursday morning.

As the son grew older, the amount of visitation by Father increased. Ultimately, Father usually exercised visitation every Thursday evening until Friday morning and every other weekend from Friday evening until…