How to Fix a Bathroom that Vents to the Attic
LESLIE: Mike in Iowa is on the line with a venting question. How can we help you?
MIKE: Yeah. I was listening to one of your shows earlier and you were talking about how the bathroom vents are vented into the attic?
TOM: Yeah. Mm-hmm.
MIKE: And I have that problem regarding that. I mean it’s right into my insulation; it’s not vented out by any means.
TOM: Yeah, yeah. A very common problem.
MIKE: I was wondering the best way – yeah, what’s the best way to fix that problem?
TOM: OK. So what you want to do is you want to install a duct – a vent duct – and you can use flex duct for this. That will take it from the bath exhaust fan to a discharge point.
Now, where the discharge point is is going to be up to you. A lot of options. Typically, you can take that out to the nearest side wall, like a gable wall, and bring it right through the wall. And you would use a termination point, a discharge point. It’s like a piece of flashing that has a hood on it and lets the air get out and then snaps shut and it keeps it from getting wet.
You could also take it and you could drop it into a soffit but you have to actually bring it through the soffit again into a grid so that it’s not obstructed. So you can take the vent and drop it down so it points towards the vented soffit right out. Or you can take it up further and point it right at an existing roof vent. Now, I don’t like that as much because I think that the higher you try to lift that air, the less effective it’s going to be. But that is an option. You can bring it straight up and point it at an existing roof vent and let it exhaust there.
MIKE: Well, my house is about six years old and I’m wondering – I’m paying pretty high energy bills regarding the heat.
LESLIE: Mm-hmm. Because what happens is when the insulation gets moist from all that moisture that’s being dumped into the attic, it completely cuts down on the R-value of the insulation. So you do need to get that vented outside, whether it’s through the siding with one of those trap doors that sort of opens out every time you’ve got it on or through the soffit. But you want to keep it the shortest run so that you can effectively move that air.
Now, if you’re evaluating what’s going on with the insulation up in the attic, you really need to look at how much compression is there, what is the condition.
Are you talking about pink fiberglass batts?
MIKE: It’s got a white fiberglass.
LESLIE: It looks like it’s blown in?
LESLIE: Yeah. You can add more blown-in, because you want it to fill up to the floor joists when you’re looking up in your attic floor. You want it to sort of reach the height of that bay and you can do that with more blown-in or what you can do is just take rolls of fiberglass and go perpendicular to your floor joists, just to sort of make up and add some oomph to the R-value. And that will really enhance your insulative value. But you do have to vent that outside.
MIKE: OK. Alright. Thank you.
TOM: You’re welcome, Mike. Thanks so much for calling us at 888-MONEY-PIT.