Learn why ridge vents are not enough by themselves to properly ventilate your attic. Learn how to add soffit vents to your home.
LESLIE: Alright, Jim, you’ve got a question about vents. How can we help?
JIM: Well, I have about a 25-year-old house that has ridge vents .
TOM: That’s good.
JIM: For some reason, these people never put vents around the edge of the house.
TOM: Now, that’s a mistake.
LESLIE: A soffit vent. Well you need them together.
TOM: It’s a system. Having one without the other is not doing you any good. See, here’s how ridge and soffit vents  work together. As the wind blows across the roof of your house, it sort of swoops up at the ridge and the ridge depressurizes and the air that’s in the attic sort of gets sucked out at the ridge.
Now, the other half of this, though, is how do we replace that air that got sucked out. Well, that’s what soffit vents are for. And also, that same wind blowing against the side of the building pushes air into the soffit wind … into the soffit vents, goes up under the roof sheeting and out the ridge vent.
And that’s a cycle that just repeats itself 24 hours a day, 365 days a year. And that’s really important because when it gets cold it takes out the moisture and when it gets hot it takes out the heat. So no matter what season of the year it is, it works very effectively. So if you only have a ridge vent, then you have one half of the ventilation  system that you need. And what you ought to think about adding is something called a continuous soffit vent.
Now, if your house is 25 years old, what do you have? Do you have wood soffits or what kind of trim do you have on there?
JIM: It’s wood.
TOM: Well, I would take … I would take the wood soffit out – completely out – and maybe consider having the fascia and the soffit wrapped in aluminum. And they have those perforated vent panels.
LESLIE: So the whole thing becomes a vent.
TOM: Yeah. So it’s wide open.
JIM: Mm-hmm. Well, I thought about just putting soffit vents around.
TOM: Well, I mean you could. The other way … the other way to do this is you could take out the wood soffit material and you could basically cut it in half. And you can buy a strip vent that is about three inches wide that would be positioned in the middle of the wood vent.
TOM: And to do that, you take all the wood soffit material down, you put up like about a four-inch piece – let’s say it’s twelve inches. So you’d put up like a four-inch piece of wood and then a four-inch vent and then another four-inch piece of wood so it becomes one long strip vent. What I don’t think you should do is cut any individual vents because you’re just not going to get enough vent area if you do that. You really want them to be wide open.
And then, the last thing to check is your insulation in your attic . If your insulation is pushed too far forward to the roof edge, it’ll block the soffit vent. So make sure it’s pulled back a little bit.
JIM: Right. It has good insulation. I do have some manual fans in there but …
TOM: Well, the thing is …
JIM: … since they’re manual they’re not efficient.
TOM: The thing is, Jim, manual fans or attic fans  are never going to be efficient. And in fact, what they can do is actually raise your air conditioning costs. You know why? Because when they run, they don’t just draw air out of the attic, they’ll draw air out of the conditioned space as well.
LESLIE: (overlapping voices) From the whole house.
TOM: That’s right. They’ll reach down to the conditioned space and pull the air conditioning out. So if you have continuous ridge and soffit vents, you don’t need those attic exhaust fans at all.
JIM: I’ll install the vents.
TOM: That’s the hot ticket.
JIM: Alright, sir. Thank you very much.
TOM: Okay, Jim. Thanks … you’re welcome. Thanks so much for calling us at 888-MONEY-PIT.