A moisture isolating reveal system includes a vertical trim piece having a fastening base configured for vertical coupling along a wall. A reveal flange extends from the fastening base. The fastening base and the reveal flange form a panel reception recess, and the panel reception recess is configured to receive a siding panel. A moisture isolation assembly extends along one or more of the reveal flange or the fastening base. The moisture isolation assembly includes: a nozzle ridge provided along the reveal flange, a moisture dam interposed between the nozzle ridge and the fastening base, the moisture dam prevents the ingress of moisture to the fastening base, and the nozzle ridge accelerates moisture moving between the nozzle ridge and an installed siding panel and decelerates moisture between the nozzle ridge and the moisture dam.