Tips For Assessing Your Needs
Proper attic ventilation consists of a balance between air intake (at or near your soffits) and air exhaust (at or near your roof ridge).
The U.S. Federal Housing authority recommends a minimum of at least 1 square foot of attic ventilation (evenly split between intake and exhaust) for every 300 square feet of attic floor space.
Always have a balanced ventilation system. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.