I have an older home that I want to install a bathroom fan into. Is it ok for the exhaust air to duct into the attic, or must it be ducted to to the outside of the house through the wall. If it can just be ducted into the attic it will save a lot of effort.I can't imagine a small amount of moisture messing up the attic.
Tom
No.
It is not OK. I can cause serious damage in the attic. Warm moist air up there can do a number of very bad things. You want the fan to move that moisture out of your home, not just move the problem to a different part of your home.
If you had done a search for bathroom fans or ventilation within this group, I'm sure you would have found a number of strings discussing your issue.
Mr. Meehan has summarised the issue nicely.
Tom Baker
The first two respondents took care of the "where to vent" question. I'll add this: There are a few different sizes of fans for bathrooms. It makes no sense. Get the one that moves the most air. Don't even think about noise level. When you finish your shower and the bathroom's almost totally devoid of steam, you'll be glad for the noise of the fan.
It's more energy-efficient to finish the shower, then turn on the fan switch, and let a humidistat turn off the fan.
Nick
Probably, but at that point, your walls are soaked. Not good for wallpaper (if any), no matter WHAT the manufacturer claims about it being made for moist environments.
I disagree. To support not using the fan during the shower though; it -would- help with male pattern shrinkage 'cause the bathroom got so cold! Stays warmer without the fan!
Pop
I think this is a bad plan. Better to vent the steam directly from the shower stall and leave the bath room dry. They make fan light combinations that are rated for over the tub use.
First of all is this bathroom used for showers? If not, you can definitely vent in the attic. If so, in spite of all oter advice, it would appear to depend on the attic venting and how well the attic is insulated. We have a fan in a bathroom used for showers that vents into the attic and have had no problems. House is now 40 years old. As usual YMMV.
LB
Why? Say 1.25 gpm of 105 F water comes out of the shower for 10 minutes, and the bathroom air is 70 F at 50% RH to start with, and we a) run a
50 cfm fan during the shower and afterwards until the bathroom reaches 60% RH, or b) run it afterwards until the RH reaches 60%...Nick
Of course, you neglected to mention where you live. That makes a difference.
Even a small amount of moisture is not good, as water vapor condenses causing leaks, wet insulation and promotes insects and fungus. I hated to do it, but I cut a hole in the roof and installed a roof vent with storm flap and bird screen. I used a generous amount of tar-based roofing caulk.
Northern NJ - Just south of Rt 80 Its about 34 right now.
LB
Either your attic is extremely well ventilated, or the steam hasn't caught up with you yet.
The venting is an eve vent at either end of this very simple attic - just a 50 X 26 rectangle. There are just two of us in the house so maybe low use is a factor.
LB
I have an older home (1920) with 2 bathrooms missing fans. What I did was to get the fan/light combo and cut out the ceiling from the fan to the wall. I then cut through the outside wall, just above the ceiling to install a vent. Connected the vent to the fan with a flexible metal snake tube (think dryer vent). After, patched up the hole in the ceiling and put a coat of textured ceiling paint over it (hides the ametuer job of patching). Connected the fan/light to same switch, so both fan and light come on when switch is turned.
Keeps the bathroom much dryer after showering. Took abolut 2 days to do each bathroom, between the installation and painting.
Me too. We have two second floor bathrooms with tub/showers whose vent fans just dump into the attic. I was concerned too, but took our builder's word that there was adequate attic venting to handle it.
Location is near Boston and the attic is vented by grills all along the undersides of the front and rear eaves and a ridge vent along the whole length of the roof.
I had about 25% of the attic "floor space" covered with plywood and put plenty of lighting up there too. We store a lot of inherited "chatckas" we can't bear to throw out up there, and go up at least ten times a year to hunt for stuff or to change filters in the HVAC air handler.
In the 19 years since we had the place built I haven't noticed anything wrong in the attic.
Just my .02,
Personally, since my toilet is in a separate enclosure than the shower, I blast the shower air into the rest of the house, which desparately needs the humidity anyway. During the summer, I have to stop doing that.
Today's Massachusetts building code requires that bathrooms have exhaust fans which vent directly to the outside. Venting to the attic is no longer acceptable Building Code 1205.2.1 .
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