Can I Combine Kitchen and Bathroom Exhaust Vents?

LESLIE: Doug in Rhode Island is on the line with a ventilation question. What’s going on at your money pit?

DOUG: I have two bathroom vents and also a hood exhaust vent over the cooktop. So I have two 4-inch vents and a 6-inch vent that I need to put through the roof somehow. And I’d rather not do it in three different vents. I’m wondering if there’s an option.

TOM: Well, the bathroom vents, if they’re near each other, could be brought together in the attic and then brought out to one termination point. You obviously don’t want to dump all that air into the attic. It’s warm, it’s moist, it’s humid and it’s going to ruin your insulation’s effect.

In terms of the kitchen vent, that I would keep separate because that could potentially be greasy. And you just don’t want to mix that in with the bathroom ventilation.

DOUG: OK.

TOM: And make sure – in all cases, I would recommend you avoid the flexible vent ducting and use metal ducting. Not the flexible metal ducting but the smooth metal ducting, because it just has less resistance as the air blows through it and it’s easier to clean if you have to.

DOUG: OK. Now, do I have to use an insulated – to connect the hosing?

TOM: No, you don’t have to insulate the ducting. That’s not necessary.

DOUG: No, OK.

TOM: Nope. Just use a solid-metal duct to do this, OK? You can buy these in home centers and hardware stores. What I don’t want you to do is use those flexible plastic ducts or flexible metal ducts.

DOUG: OK. I gotcha.