a ventilator comprising a base having a central opening with inner and outer housings , the outer housing being pivotably connected to the base with the inner and outer housings being secured together accounting for the slope of the roof , and a vent section having a vent passage permitting egress of air from within the housing , deflectors located about the vent passage to deflect rain from entering the same . the ventilator is preferable formed of a plastic material and the structure permits easy adjustment thereof .