As many people replace their roofs today, the exhaust ventilation of choice is a Ridge Vent. There are many manufacturers and types of ridge vents just as there are with power fans and turbines. However, not all homes are created equal. A very important aspect that should determine if you choose a ridge vent is the amount of ridge your home has. Even today we see large hip roofs with very little ridge having ridge vent as the roof exhaust and a power fan under the ridge vent is also very common to see. This combination does nothing to help exhaust the heat from the attic space. There should be a balance of intake (soffit) and exhaust (ridge vent or power fans) that follows the FHA 1/300 rule. GAF has a great calculator to figure out what is needed.
Click GAF Ventilation Calculator to view.
Not only does a small ridge line with a large eve line not balance, but the power fan and ridge vent in the scenario listed above, swap air and do nothing to relieve the attic from the static hot air that has built up. Typically a hip roof should have 1 power fan per 1500 square feet of roof to best exhaust ventilate the heat in the attic space. Of course this depends on the strength of the power fan. Yes, ridge vent is a great product that is passive and creates a natural negative air pressure but each roof is in need of its own type of ventilation. So, when looking to properly ventilate your roof always consult with a factory certified roofing contractor to hear the best options for your roof.