Should I Have More Than One Type of Attic Vent?

March 10, 2023

Absolutely, yes! Your attic ventilation works on the simple property of physics in which hot air rises. For that principle to apply to your attic, you must have vents at the top of your attic to exhaust the hot air. But that means you also need vents down low to supply more air to replace what is leaving at the top.

Think of a fireplace and chimney.  Balance is key to the whole cycle working effectively. You want a 50/50 balance between incoming, cooler air from down low and the outgoing, hotter air leaving up high. Please refer to our article on types of attic vents to better understand their location and function.

How Many Attic Vents Should I Have?

Keep in mind that more is not always better. It is all about balance and location, location, location. Air flow in an open attic is very opportunistic, meaning a ridge vent at the top of the attic will pull air from the closest source so that it can work properly, even if it means pulling air from another exhaust vent. This flow patter can be observed on older homes with existing gable vents or turbines, and where ridge vents were installed when the roof was replaced. The ridge vents incorrectly draw air from the turbines and creating stagnant air in the bottom of the attic.

Attic ventilation works to the extent allowed by the most restricted vents. So, a lot of soffit vents all around the house will not move much air through the attic with only one turbine at the top. The same principle applies in reverse as well.

Balance is critical, but the volume of air (as determined by the capacity of the installed vents) that moves through the attic is just as important. Three or four soffit vents coupled with one turbine may represent balance but will not adequately ventilate the attic of a typical home. Local building codes provide minimum requirements for attic ventilation. 

If you suspect there is poor attic ventilation in your house, contact your local building permit office or ask licensed building contractors for opinions of proper function of your attic ventilation.

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