Why is my attic fan pulling air from the roof vents instead of the soffits?

That short-circuiting is a textbook example of why mixing powered and static ventilation usually fails. Your fan is taking the path of least resistance, wich is those nearby box vents, rather than pulling from the soffits. You’re essentially just cooling a three-foot radius of your roof deck while the rest of the attic stays stagnant. I whould definitely not bother with the flexible hosing idea. It’s a total headache and won't work because the friction in those hoses will kill the airflow anyway. Sealing the two closest vents with some plywood or flashing is a better temporary test. If you do that, watch the thermostat on the fan to see if the attic temp actually drops. But keep in mind that even if you seal them, the fan might just start pulling from the remaining static vents or, worse, sucking conditioned air out of your house through the ceiling. The bigger issue in a climate like Atlanta is that powered fans often create a **negative pressure** situation. If your soffit vents aren't perfectly clear or aren't large enough to feed that fan's CFM requirements, it’ll pull air from your light fixtures, plumbing stacks, and top plates. You end up paying to cool the attic with air you already paid to refrigerate downstairs. Before you pay for that insulation top-off, you really need to prioritize **air sealing**. Get a few cans of spray foam and seal every single wire penetration, top plate, and light box you can find in the attic floor. Once that’s done, you might find that disabling the fan and letting the static vents work on thier own is actually more efficient. If you really want better airflow, adding a couple of gable vents is a much more reliable afternoon project than trying to redirect air to a short-circuiting fan.

Oh man, I am so stoked to finally be learning about this stuff! I'm just getting started with my own attic project because I want to turn it into a workout space this summer. Do you think the color of the shingles makes a huge difference in how much the fan has to run? Mine are almost black and it feels like a furnace up there. Also, if I eventually put a small portable AC unit in the attic, would that completely ruin the airflow balance you guys are talking about? I'm trying to plan ahead so I don't regret it later!

You’re at R-25 with that 8 inches of fiberglass. In Atlanta, you need to hit R-49 or R-60. I’d blow in some GreenFiber cellulose to get the depth up to 17 inches after you air seal. Check if you have baffles like the Owens Corning Raft-R-Mate in every rafter bay. If those aren't clear, your soffit vents aren't doing a thing. Those powered fans ussually pull about 1,200 CFM but most older homes don't have the Net Free Area to support that intake. Honestly, I’d ditch the fan and the box vents for a continuous GAF Cobra ridge vent. It’s way more reliable than mechanical fans that eventually just seize up in the GA humidity.

Honestly, I’d just kill the power to that fan. I’ve been there, and those powered vents ussually cost more in electricity and sucked-out AC than they’re worth. If you’ve only got six static vents, you’re better off adding more of those or a ridge vent down the line. Also, check your soffits from the outside. I spent a whole weekend thinking mine were clear, but the previous owner had basially painted over the screens. Doesn’t matter how much fan power you’ve got if the air can’t acutally get in from the bottom. If they’re blocked, your fan’s just gonna keep pulling from the house.

I'm still trying to wrap my head around all this, but the negative pressure thing is scary—I definitly don't want to pay to cool my attic with my AC! How do I even find those top plates or wire holes if they're buried under the current insulation? Do I have to move all eight inches of fiberglass out of the way just to see them?

Also, is there an easy way to check if the soffit vents are actualy pulling air? I’m not great with heights, so if there’s a trick that doesn’t involve a 20-foot ladder, I’d love to hear it.