Should I Replace An Attic Fan with a Ridge Vent?
LESLIE: Alright. We’re heading out to Delaware where Mary has got a question about a roof. What’s going on at your money pit?
MARY: I have a two-story house with three-tab shingles that are 25 years old. And I’m about to replace them with architectural. I have an attic fan currently. It’s about 30 years old and I don’t really have to keep that. But my question is regarding a replacement attic fan versus the ridge vent.
TOM: So, we would definitely recommend a ridge vent over a replacement attic fan, for a lot of reasons.
Here’s why. In the summer, many times folks will install attic fans to try to cool their attic thinking that it will lower their cooling cost. But what generally happens is when an attic fan kicks on, it will depressurize your attic. And then it needs to replace that negative pressure. So what will happen is it will reach down into your house and actually pull some of that air-conditioned air up into the attic.
Now, how that happens is interesting. It’ll pull it out from gaps around, say, where your attic door is or it’ll pull it through the walls, through gaps around plumbing pipes or electrical wires or outlets that go through. There’s usually some sort of thermal connection between the inside and the outside. And by using an attic fan, you’re going to potentially drive the cooling costs up, not down.
A better option is a ridge vent – a continuous ridge vent – that goes down the peak of the entire roof. And that will exhaust attic air. But the ridge vent should always be matched with soffit vents at the overhang of the roof so that the air will enter down low in the roof, roll up underneath the roof sheathing and then exit at the ridge. And that sort of convective loop will do a much better job of keeping your attic cool than an attic fan. It will not – and it will not drive up your cooling costs.
MARY: And you’d close off the current attic fan?
TOM: That’s right. I would actually – if you were going to be replacing your roof, I would simply take that whole fan out, tap off the wires and disconnect it. You don’t need it.
MARY: OK. The other question is I also have a whole-house fan, which I rarely use. Can you still use a whole-house fan with the ridge vent?
TOM: Yeah, absolutely. Now, let’s talk about the difference between a whole-house fan and an attic fan. An attic fan is just that: it draws air out of the attic. A whole-house fan is mounted, generally, on the ceiling of the upper floor of the house. The whole-house fan is going to draw air from your house itself, push it up into the attic where it will be exhausted.
Now, the key with a whole-house fan is you have to have enough exhaust ventilation up in the attic. If you end up having a continuous ridge vent and continuous soffit vents, I think you probably will have plenty of exhaust ventilation up there in the attic.
I would suggest, if you don’t have it already, to put that whole-house fan on a timer. Because it’s really effective, especially at night, when you can set it for an hour or so, when you’re going to sleep, to kind of keep that air moving through the house. And then it’ll just go off by the time you fall asleep and the air gets cooler.
MARY: Vents in the eaves in the house, which were built in the house, are they closed off when you get the ridge vent?
TOM: Generally, yes. Those small vents that are on the ends of the gable walls, you do want to close those off and make sure you have continuous soffit and ridge vents. Because you’ll get some turbulence between the ridge vent and that end gable vent that can impact the flow of the air.
MARY: Alright. Hopefully, that’s what I need and I’m about to call a contractor tomorrow.
TOM: Alright. And now you know what to get done. Thanks so much for calling us at 888-MONEY-PIT.