Should you upgrade your box vents on your roof?

Box vents are better than no attic ventilation. However, it is usually recommend to upgrade box vents to an active ventilation system.

Box vents are popular because they're the cheapest type of roof vent you can find. But because they’re the cheapest, box vents are also the least effective type on the market.

Attics require a minimum of 1/150 of net free area (open area for air to pass through). This means that for each 150 square feet section in the attic, 1 square foot of net free area is required for ventilation.

For example, let’s say you have 1500 square feet in your attic.

A standard size box vent has 50 inches of net free air space. This means you would need 8 box vents to ensure your attic is properly ventilated.

On the other hand, a 14” turbine vent has 150 inches of net free air space, plus a drawing effect to move the air around. Compared to 8 box vents, you would only need 2 turbine vents for the same attic space.

At the end of the day, it’s up to you if you want to upgrade your box vents. But any active roof vent is functionally better than a box vent.