I'm planning to install a gable fan in my small rectangular house (around 900 square feet) that has gable vents on opposite sides and two passive roof vents. I want to cut a hole in the north gable to install a fan that will pull air from the south gable vent to ventilate my attic effectively. However, I'm concerned if the fan will only pull air from the nearest roof vent, leaving a majority of my attic unventilated. Should I keep the roof vents or remove them before adding the fan?
4 Answers
Be sure to check the venting codes in your area. There are recommendations for how much intake and exhaust venting you need based on attic size. Usually, you want around one square foot of ventilation for every 150 square feet of attic. If what you have isn't up to code, it might not be enough ventilation for your needs. Adding a vapor barrier can also reduce how much venting you need, but a steeper roof may require more.
It really depends on what you're trying to address. Are you dealing with heat in the summer, or is it more about humidity in the winter? Typically, if your roof is properly vented, you might not need a fan. Have you checked the insulation above your ceiling? That plays a big role too. And do you have soffit vents? That's important because air should ideally flow in from the soffits and out through your roof or gable vents.
The placement of your static roof vents can really mess with airflow. Sometimes, they can pull from adjacent vents instead of creating a good cross breeze. It can lead to uneven air circulation in your attic.
If you're in the Northern hemisphere, I’d suggest cutting a hole in the North side to add your fan. This way, you’ll pull in cooler air from the North instead of hot air from the South. That’s what I did in my house in Arizona, and I have no roof vents. You can check how well it's working by holding a piece of paper up to see the airflow. If it's just pulling from the roof vents, you might want to cover them from the inside of the attic.
Yeah, it's definitely too hot in the summer here! I have an evaporative cooler but it barely helps. I also have concrete block walls that hold heat a long time. The county confirmed my insulation is good, but I don’t have soffit vents.