I cannot for the life of me figure out where this excess moisture is coming from. My bathroom has humidity about 10% higher then the rest of the apartment. The living area is fine. I check the humidity on a Humidity monitor and it is always very high in the bathroom, around 68% The thing is its only 30% humidity outside so its not coming from outside. I have a fan that I use every shower and leave the door open. If I open the window it drops to about 58% (that is with the outside being 30%) It won't get lower then 58. As soon as I shut the window it goes back to 68 or so. I see no leaks under sink, no condensation on toilet. I don't know where this is coming from. I live on the 2nd floor of a 3 floor apartment complex that is only 2 years old. I have lived on the 2nd floor of a 3 floor complex before and never had this problem. And that bathroom didn't even have a window. This one does. I don't get it. Can someone tell my why it is so humid? What gives?

  • 1
    Do you have an exhaust fan? I know some places that have a window do not require a fan. My shower creates a bit higher level but my wife loves very hot showers and the fan can not keep up so the walls and ceiling get damp causing the levels to be quite high all day
    – Ed Beal
    Feb 26 '16 at 0:20
  • Yes I do have and use the exhaust fan, plus open window after, and leave door cracked. Thing is it will be 24 hrs after any shower and still that high humidity.
    – Jenn
    Feb 26 '16 at 0:23
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    Are you sure your humidity meter is accurate? They aren't that easy to get right. Feb 26 '16 at 1:24
  • What type of heating system do you have?
    – Tester101
    Feb 26 '16 at 3:13
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    Are you sure that the fan is clean and functioning? One test that I've seen listed before on other questions is to rip off a piece of toilet paper and hold it up by the fan. If the fan grabs and holds it up, then it's working. If not, this could be the problem.
    – TFK
    Feb 26 '16 at 5:48

Definitely get the Landlord involved. Unless there's a standing pool of water, much bigger than the toilet, there's no apparent nor logical reason for any room to stay so noticeably different.

I'd say maybe a backdraft through the exhaust fan from a faulty damper, but you've disproven that. In the meantime, check with the neighbors & see if either are doing anything strange or noticed the same thing.

I'd suspect the 1st floor got a Hot Tub or started Indoor Gardening. A Room Humidifier or Air Conditioning System's Humidifier wouldn't even do anything like your saying.

  • I do wonder if opening the door and the window AND turning on the fan is somehow drawing in moisture. I find that my bathroom gets the most out of the exhaust fan when it's JUST the fan on, and enough of a gap at the bottom of the door. Feb 26 '16 at 13:56
  • Yeah, that's what I was thinking initially but she disproved that pretty handily. You're definitely right though, using the fan with only the door gap or the open interior door as the only air feed is the optimal operation. I'm assuming she's actually feeling the difference & not just playing around with some new Phone App.
    – Iggy
    Feb 26 '16 at 14:11

Firstly, when your fan is running DO NOT open your bathroom window. Open one elsewhere and have your door ajar of if there is a good gap at the botton close it. Why? What you are looking to do is draw air ACROSS the bathroom space so the warm moist air is picked up and drawn out. By having the window open you have what's effectively a short circuit so air flows in through the window and immediately out of the fan picking up almost no moisture laden air on its journey.

It's important to keep the fan blades and duct clean as that encourages best flow rates.

Try this test. Put a candle night light on the floor by the door withh the door closed and the fan on. Watch the flame dance. Then open the window and watch the flame sit bolt upright. That tells you there is no through draught.

Make sure your fan runs for a good while post showering.

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