LESLIE: Brent in Texas is on the line with a venting question. Tell us what’s going on.
BRENT: My question is about ridge venting. I’ve seen a couple of different places where people said, “Well, you can’t use the gable venting in conjunction with the ridge vent. It’d change the draw.” Of course, in the old balloon construction, the draw really comes up the balloon framing and vents into the attic, which goes out the gable vent. Would those need to be closed off? Would it work well in conjunction with each other or can I just stick with what’s there?
TOM: Well, the most important part of a ventilation system you didn’t mention and that’s at the soffits. Are you going to have soffit venting on this house?
BRENT: Well, since it is vented though the balloon framing now, I wasn’t sure if I really needed to add soffit venting, as well.
TOM: The best ventilation system that you could have – and I wouldn’t count much on the ventilation through the balloon framing, because that’s presuming that the home is going to be pretty drafty. But remember, the purpose of that ventilation is to dry out the insulation that’s in the attic space. The best way to do that is with a combination of ridge and soffit vents, because they work together.
And how they work together is that the wind blows and it presses up into the soffit vent, rides up under the roof sheathing and then exits at the ridge. The ridge is always in a depressurized area of the house, because the wind hits that and sort of bounces off the roof and goes in a circular motion, which causes a draw at the ridge. And then, so, the positive pressure at the soffit goes under the sheathing, goes out at the ridge.
Now, your question is: what about the gable vent? And the answer is you should block it off, because it does interrupt that flow of air from the soffit, under the sheathing and out the ridge. By having the gable vent, you get some sort of turbulence up there that interrupts that flow. So if you can have a soffit vent and a ridge vent, that’s the best situation. If you’re not going to have a soffit vent, frankly, it really doesn’t matter, because you’re not going to have the pattern that we would like you to have and you just have another hole in the space to let air out.
But if you want to make it really efficient, put in soffit vents, put in ridge vents. And then if the gable vent comes through the wall in an old Queen Anne and you want to leave it for appearances, that’s fine. Just put something across the back of it so it doesn’t actually let air in.
BRENT: Alright. Well, that does help out. I appreciate your help.
TOM: You’re very welcome. Thanks so much for calling us at 888-MONEY-PIT.