A panel installation assist device for supporting one end of a panel during installation includes a bar, which has a set of holes extending therethrough from a first face thereof. Respective holes are selectively alignable with studs or rafters. Mounting hardware inserted through the holes mounts the bar to the studs or the rafters. The bar has a set of orifices positioned therethrough, each of which has a spirit bubble tube positioned therein, which is engaged to the bar. Respective spirit bubble tubes indicate an orientation of a longitudinal axis of the bar relative to horizontal and vertical. A notch extends into the bar from a first edge thereof and the first face, and between opposed ends of the bar. The notch is configured for insertion of an edge of a panel so that one end of the panel is supported by the bar to facilitate installation of the panel.