Attic Ventilation

Find out why a properly vented attic helps reduce your air conditioning costs and prevents problems like ice dams. Get tips on using ridge and soffit vents and learn whether you can have too much attic ventilation.

LESLIE: Well, a well-sealed home can actually help you keep energy costs and your energy bills down as well as your energy usage. But there is one space in your house that should be drafty and leaky.

TOM: That’s correct and it’s your attic. Joining us now to tell us why is This Old House host Kevin O’Connor and the show’s general contractor, Tom Silva.

And guys, to most homeowners, this is exactly the opposite of what they think they should be doing to the spaces in their house.

KEVIN: Attic ventilation is a topic that confuses a lot of people. Usually we’re trying to seal up a house to improve its energy efficiency. But when it comes to attics, that’s just the opposite case.

TOM SILVA: Well, you’re right. If your attic is unconditioned space, it must be vented. A properly-vented attic will prevent ice dams in cold climates; it’ll reduce your air conditioning cost in warm climates; and it’ll extend the life of your roof no matter where you live. But the type of ventilation that you have is important. A soffit and a ridge vent work together, so it’s very important that the soffit vent is not blocked by insulation. You want that cool air from under the soffit to enter the attic, cooling it; drawing the warmer air out through the ridge vent.

KEVIN: And then what about gable end vents?

TOM SILVA: Well, gable end vents work good with a soffit vent but they don’t work well with a ridge vent. The ridge vent will actually pull the air in through the gable vent, not through the soffit vent. So air will take the path of least resistance.

KEVIN: Alright, some good tips and we’ve got more information on attic ventilation on ThisOldHouse.com.

TOM: So a drafty attic, a good thing; drafty house, not so much. (chuckles)

KEVIN: (chuckles) Exactly.

TOM: Tom Silva, Kevin O’Connor, thanks for stopping by The Money Pit.

TOM SILVA: My pleasure.

KEVIN: Good to be here.

LESLIE: And remember guys, there’s one time that you don’t want a drafty attic and that’s if you’ve got a finished attic (Tom chuckles) and you guys are living up there, it’s a playroom. Whatever it is, if you’re using that attic space as living space, it should be properly insulated and not drafty; unless you’re opening those windows. (chuckles)

TOM: Good point. And for more tips on how to take care of your house, we encourage you to watch Tom and Kevin on This Old House Television. This Old House is brought to you by GMC. GMC – we are professional grade.