A modular guide frame for use with gates of various thicknesses is assembled from separate side portions. The side portions are provided with hubs, having facets of different widths. The hubs may be coupled with one another to align the facets and provide different gate guide configurations, having various channel widths. An extension plate may be coupled between the side portions to further expand the width of the channel. Elongated sealing members may be secured within the channel to further customize the fit between the guide frame and a gate. The symmetrical nature of the side portions allow them to be manufactured from a single extrusion form, while retaining the ability to be used with one or more differently sized gates.