Attic geometry definitely throws a wrench in the works. I’ve seen plenty of older homes with weirdly shaped attics where gable fans just end up recirculating air in dead spots—doesn’t do much good. I’ve measured pressure differences a couple times (using a manometer, nothing fancy), and honestly, if you don’t have enough intake, the fan just starts pulling from the house instead of outside. Baffles and vent chutes help, but only if you’re sealing up the rest of the attic tight. Otherwise, you’re basically air-conditioning your neighborhood... which isn’t great for the power bill.
I’ve been struggling with a similar decision. My attic layout’s kinda weird—lots of nooks and angles, so I was leaning toward a roof-mounted fan. Gable fans seem like they’d just move air around the high spots and not actually vent much. But now I’m worried about the intake vents after reading your post... I don’t want to start pulling cool air from inside the house. Did you add more soffit vents or just seal everything up tighter? I’m finding it tough to balance airflow without messing up the insulation.
I ran into the same thing last summer—my attic’s chopped up with weird angles, and the roof fan made more sense to me too. But yeah, intake is where it gets tricky. I ended up adding a couple extra soffit vents after I noticed the fan was pulling air from the hallway instead of outside. Didn’t bother sealing everything tighter, just made sure the insulation baffles weren’t blocked so air could actually move through. It’s a balancing act for sure, but the extra vents really helped in my case.
It’s a balancing act for sure, but the extra vents really helped in my case.
That’s spot on about the intake being the tricky part. I’ve seen way too many folks throw a big fan up there and then wonder why it’s sucking AC out of their house instead of pulling in outside air. Like you said, it’s all about balance. I had to add more soffit vents too—wasn’t thrilled about cutting more holes, but it made a noticeable difference. Skipping the air sealing is a gamble, but if the baffles are clear and you’re not seeing moisture, I can’t really argue with what works. Sometimes “good enough” really is good enough.
I had to add more soffit vents too—wasn’t thrilled about cutting more holes, but it made a noticeable difference.
That’s exactly where I landed—more intake, less regret later. I’m curious, for those who went with gable mount fans, did you notice any issues with uneven cooling or hot spots in certain sections of the attic? I’ve heard the airflow can get weird if the roofline isn’t symmetrical or if there’s a lot of framing in the way. I keep going back and forth on whether a roof mount is worth the extra hassle, especially with a lower pitch roof.
