Abstract: A roof vent damper for closing a roof mounted ventilator in the event of a fire includes a frame formed from an elongated rectangular plate having a central dumbbell shaped cut-out. Longitudinal side edges of the plate are folded over to form parallel guide track members. The plate is then folded along a central transverse line extending across a narrow central portion of the cut-out to form overlying plate members separated by a hollow guide track. A damper plate is received for reciprocal sliding movement in the guide track and is retained in an open position by a fusible link which separates at a predetermined elevated temperature. The damper is biased to a closed position by a coil spring.