The type of vents utilized in ventilation will be determined by the home itself.  We design ventilation solutions consistent with FHA recommendations.  We will need to determine if adequate intake ventilation is present, then evaluate roof for proper exhaust vents.  Most gable roofs with adequate intake and a continuous attic are suited for an external baffle ridgevent. Hip roofs are often short on enough ridge area to balance the intake.  When this condition exist we will seek alternative exhaust vents such as an Attic Breeze Solar Powered ventilator or a combination of passive vents. jb