Eliminate Condensation on Bathroom Walls

LESLIE: Phil in New Hampshire’s steaming it up in the bath. How can we help?

PHIL: Hi, we have a 5×8 bathroom with a ceiling exhaust fan. And we have five people at home taking showers every morning and the walls are just – steam is just dripping down. And just wondering what we could do to try to correct this problem.

TOM: Well, the first question is do you use the exhaust fan, Phil?

PHIL: Oh, yeah.

LESLIE: Do you leave it running?

PHIL: Oh, yes.

LESLIE: OK, because you should leave it running about 20 minutes or so after you shower, just to get that excess moisture out of the air.

TOM: Yeah. And the next thing, Phil, is this fan that you have – is it exhausting outside?

PHIL: No, it is exhausting in the attic.

TOM: Ah ha! Big mistake.

LESLIE: Which is probably helping circulate that moisture right back into that room.

TOM: Yeah, big mistake.

LESLIE: And you’re putting that moisture right up in the attic, which is going to encourage mold growth up in the attic.

TOM: And make your insulation ineffective.

You need to improve this ventilation system. First of all, it sounds to me – my gut is telling me that the fan is not big enough. You know, with that kind of heavy use of the bathroom like that – and especially if it’s – if the attic is mounted right above it – what you might want to think about having is an inline exhaust fan. Basically, this is the kind of exhaust fan that you may often see in a hotel; where you don’t actually hear the fan come on but you know it’s working because the air is sort of getting sucked into it. It’s a much more efficient way to do it and the way it works is the fan itself is mounted sort of in line with the exhaust duct in the attic. So when you throw the switch, the fan kicks on but you don’t hear the whoosh of it. It also can move many more cubic feet of air than just the kind that’s ceiling mounted.

PHIL: That sounds great.

TOM: Well, that’s the least that you should do; connect a duct to that and duct it to the outside.

LESLIE: And then once you fix this problem, you should think about re-insulating the attic; checking all of that wood and lumber in the attic to make sure there isn’t any moisture damage; and then, also, looking at your drywall situation in the bathroom. Because if they’ve become too laden with moisture, it might be time to re-drywall.

TOM: PHIL, thanks so much for calling us at 888-MONEY-PIT.