# excessive moisture on bathroom ceiling



## Den69RS96 (Mar 2, 2007)

What can I do to make sure my ceiling is not soaked after a shower? The bathroom is about 8 x 10 and the fan we have is rated a 110 cfm. I think the fan is big enough, but its obvious that all the steam from the shower is collecting on the ceiling. My house was built in 2005 and have plaster walls and ceilings. Last year I had a few mold spots on my bathroom ceiling. I used a mold remover to clean my ceiling. I then washed it down with soap and water. When it was dry, I coated the ceiling with Kils primer, then a top coat of benjamin moore white ceiling paint. Well, the paint is bubbling and peeling and I've scraped and recoated those areas. I can tell this will be an ongoing issue unless I do something, but I'm not sure how to fix it. Do I install a bigger fan?


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## AllanJ (Nov 24, 2007)

1. Leave the door open to let the air in the rest of the house carry away the moisture.

1a. Have a room fan blowing into the open bathroom door.

2. Open the bathroom window (if there is one).

3. Install and use a bigger fan. Is the duct to the outside (must not be into the attic) unobstructed?

3a. If the duct runs through the uninsulated part of an attic, you need an insulated duct.

4. Keep the shower curtain or shower door open when the shower is not in use.

5. (Off topic) If the bathroom ceiling is an exterior boundary such as below the uninsulated region of an attic, it may need more insulation.


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## Den69RS96 (Mar 2, 2007)

Leaving the door open isn't an option all the time. Its a master bathroom and I shower before my wife wakes up. The fans duct work goes into the attic and vents through the suffet. The duct work is insulated as is the ceiling in the attic. They blew in insulation and there is a lot of it everywhere. Opening the window helps, but when temps drop here in the northeast I prefer not to open the window as it can get real cold. I was wondering if installing a fan over the shower would help or if I should install a more powerful fan. The fan I have now is a nutone LS100L 110cfm with a light in the center. It generates enough suction tol hold up a cleanex, but nothing heavier.


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## jte1130 (Jan 8, 2008)

Den, I had a similar experience in an apartment I lived in. I couldn't do anything to cut down on the moisture but I learned a lesson about ceiling paint. When I first painted I used BM Ceiling White and had the same bubbling/peeling experience. Next time around I used BM Decorators White in a high gloss finish. It made it much easier to wipe/clean and prevented the bubbling/peeling.


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## jogr (Jul 24, 2007)

If your bathroom is too tight then you could be starving the fan and a bigger fan won't help. Is your bathroom door tight at the bottom or does it allow air flow underneath? Did you do the kleenex test with the door open or closed?

Also check that the fan and duct aren't partially blocked.

Putting in a flow restricter in the shower nozzle to reduce the volume of water may also help. 

Make sure you run the fan after the shower until the humidity is gone (you can put in a timer switch) and leave the door open after you're done.


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## TroyM (Dec 24, 2007)

Quit taking hot shower. :laughing:


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## ron schenker (Jan 15, 2006)

jogr said:


> If your bathroom is too tight then you could be starving the fan and a bigger fan won't help. Is your bathroom door tight at the bottom or does it allow air flow underneath? Did you do the kleenex test with the door open or closed?
> 
> Also check that the fan and duct aren't partially blocked.
> 
> ...


That's what I was gonna say but I'm too slow!
Excellent advice:thumbsup:


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## troubleseeker (Sep 25, 2006)

That size fan should be ample. Are you sure it is working okay? Perhaps the damper is stuck shut, or if it terminates in a side wall vent a bird has built a nest in the vent, blocking the flapper from opening. Is it attic space above the bathroom. Could be a lack of insulation or poor installation allowing the top side of the ceiling to become very cold, thus when the warm air in the bathroom contacts the ceiling, it condenses into water.


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## Den69RS96 (Mar 2, 2007)

There is about a 1/2 or more gap under the bathroom door. I did the kleenex test with both the door open and closed. It is able to hold it up in both cases. The original coat of paint is not peeling, I think it was Sherman Williams. The coat I put on was Benjamin Moore. Maybe I'll try a different ceiling paint. 

The attic is directly above the bathroom and has a ton of insulation over it. I just read that the duct work should go straight up through the roof, however mine duct work runs parrallel with the ceiling and exits through the suffet vents in the attic. The end of the duct has a screen type housing covering it. I'll check to make sure it isn't clogged with a bee's nest or something. I beginning to think the way the duct work is run and the BM paint are the mains sources of my problem. Thanks


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