A baffle vent is formed to span several roof rafters in a panel form with alternating flat ribs and rounded valleys extending along the longitudinal length thereof. The spacing of the flat ribs is four inches on center so that the transverse width of the panel will be engaged properly with roof rafters spaced on a multiple of four inches. The baffle vent includes uniformly spaced transverse ribs that extend from one transverse edge of the panel to the other to stiffen the panel which is formed of vacuum molded polyvinyl chloride film. The baffle panel is placed on top of the roof rafters before the roof sheeting is applied so that the insulation will force the baffle vent against the roof where the flat ribs engage the roof sheeting and the rounded valleys provide a passage for air to flow from the building soffit to the roof vent.