Installing Ventilation for a Bathroom Fan
LESLIE: Lou in Maryland listens to The Money Pit on WJFK and you’ve got a question about a bathroom vent. What can we do for you?
LOU: Well, what I’m looking to do … I’ve got a … in our master bathroom – so it’s upstairs second floor – there’s no fan; there’s no (audio gap).
TOM: Yeah, isn’t that crazy? You know, the builders are not required to put a fan in a bathroom …
LESLIE: Is there a window in the room?
TOM: … if there’s a window.
LOU: Yeah, there’s a window; absolutely. But …
TOM: So why don’t you just pop that open in January, why don’t you? (laughing)
LOU: Well, that tends to happen; but the wife doesn’t like that so much because then it cools down the …
LESLIE: Because we’re always cold in the shower. (laughing) I can’t tell you how many times I’m in the shower and my husband leaves the door open. And I’m like, “It’s freezing in here,” and he’s like, “It’s hot.”
LOU: Yeah, you can’t see the mirror soon as you get out, you know? Because everything gets all fogged up.
TOM: So what do you want to do? Put a vent fan in there?
LOU: I would like to put a vent fan in there but my question is do I need to vent it outside or can I just vent it into the attic?
TOM: Oh, no.
LESLIE: Vent it outside.
TOM: Right. You can’t vent it in the attic; that’s a big mistake. You know why? Because all of that moisture will condense in your attic and it’ll get into your insulation. It could rot out your sheathing and if it gets the insulation damp, it makes it completely ineffective. Insulation, to insulate, has got to be dry. If you get it humid, it doesn’t work.
LESLIE: So get that elbow bend.
TOM: Yeah, Lou, you can go up to the attic and then like across the insulation then, maybe, down into the soffit area. Or you can go up toward a vent or you could put another vent through the roof. So you can go through the attic space; but just don’t leave it right in the attic.
LOU: That’s a good … I didn’t think about that. Because I think there’s a ridge vent up in the attic. Could I like vent it up into that?
TOM: Well, if it’s a big enough ridge vent. Ridge vents tend to need a lot of length to do a good job venting. I’d rather see you bring it down to the soffit vent and open up a space in the soffit and have it vent down.
LOU: Okay. So just the fact that it will, then, go up and then down …
TOM: Well, I just don’t think that the ridge vent’s going to be big enough, by itself, for it to vent all of the air that’s going to come through that fan. I think if you take the exhaust duct, run it across the top of the insulation, drop it into the soffit and then cut a whole in the soffit and terminate the vent there, then you’ll have no restriction whatsoever and you’ll get all of that warm, moist air out very quickly without causing any damage to the attic structure itself.
LOU: Plus, there’s not a … plus, I don’t have to worry about rain getting in there or anything like that, as far as having a vent (inaudible).
TOM: Exactly. Gravity’s working for you in that case.
LOU: Gotcha. Okay.
TOM: Okay, Lou?
LOU: Will do. Thank you very much.
TOM: You’re welcome. Thanks for calling us at The Money Pit.