Abstract: Trim bands and a trim band system for custom fitting siding is presented. The trim bands include a base band, a frieze band, a mid band, and an inside corner band which function to retain the rough edges of siding panels without exposing channels thereby providing a custom fit and enhanced aesthetic appearance. The trim bands are one piece continuous members which comprise varying numbers of portions which depend on the structural area of the building for which the trim bands are designed. The trim band system includes securing a plurality of trim bands to the exterior surface of a building followed by the placement and attachment of siding panels in conjunction with the trim bands to conceal all exposed edges of the siding panels without exposing channels or troughs formed within the trim bands.