Abstract: A cap which can be attached to a roof vent pipe to form a closure for the roof vent pipe after the usual ventilating device attached to the roof vent pipe has been removed thereby trapping hot air in the attic area of a home or other building. The roof vent cap is of one-piece unitary construction secured in place by anchoring screws which may be the same screws that secure the roof ventilator in place with the cap including three depending cylindrical flanges of different lengths which can be mounted on different diameter roof vent pipes thereby rendering the cap universal in use. The variation in length enables access to anchor screws on each of the flanges.