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Old 08-28-2010, 03:00 PM  
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Default Mystery Stains on Bathroom Wall

We live in a fairly newly built house. Built 6 years ago. We have noticed some stains along the bathroom ceiling near the molding. The attic is directly above the bathroom but we could not find any water leaks and the attic is bone dry. We can't figure out where the stains came from. The good news is that the stains are not growing in size. Any opinions on what this might be?

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Old 08-28-2010, 09:38 PM  
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You know, you'd expect a punch line after the phrase "mystery stains on bathroom wall"! Ok, ok enough of that, however it appears to be moisture related. Do you have a vent in your bathroom? Was the proper type of paint and premier used in the bathroom?

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Old 08-29-2010, 06:22 AM  
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It could be moisture...or it could be a paint issue.
I have seen this before when the builder, does not use the same primer at all areas of the wall.
It looks like someone painted the crown moulding , then did the area of the wall around the crown moulding. Then painted the other wall area after they cut in around all the trim. This could be the issue, you just never noticed it.

This happens when the light gets different also. Like when you work different hours, or buy a new fixture, folks see things that where never there.

If it is water, is it actually wet?Did you poke it or test with a moisture meter? If you need to, get a pro in there to help you, you do not want this to go any further, Mold grows fast.

Good luck.
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Old 08-30-2010, 05:55 AM  
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Is this bathroom used for showering? If so do you use an exhaust fan? If you have a fan, is it properly ducted to the outside and not covered with insulation?

Also,is this an outside wall, is it properly insulated? Moisture always travels to a cold surface, it maybe a condensation issue.

And what is the surface of the other side of the wall?
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Old 08-30-2010, 10:26 AM  
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Another possibility.

The areas are a little colder due to improper insulation above those areas. The colder areas can become moist when the humidity is high in the bathroom. Imagine a cold beer on a hot day, the can/bottle becomes wet. Same thing. The most areas attract dust/dirt or possibly support mold growth.

To test it. Take a q-tip, dip it in some bleach and run it across the stained area. If the area cleans from the bleach then its mold. If it stays dark its dirt/dust.

Either way you can probably just clean it. If mold use a bathroom cleaner with designed for mold. If dirt just use some general purpose cleaner Pine-sol, spic and span, whatever.

If cleaning doesn't make it go away then, as suggested, its a paint color issue.

To keep it from coming back (if its dirt or mold from cold spots) you should increase venting of the bathroom and make sure the insulation above is correct.

Let us know what you find out.
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Old 09-05-2010, 09:40 AM  
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Thanks everyone! based on the replies, we think that this may be a venting issue. We do shower and there is no proper venting in this bathroom because of the design of the ceiling of the bathroom.

Thanks Handy guy for the tip! I will try out the q-tip suggestion.
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Old 05-05-2012, 02:37 AM  
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Based on the picture as well as you information, I guess it's not a stain. It's another problem due to the painting or the coating under the painting. Because stain looks different and you said that it do not spread over to your wall. And also, you make sure you have exhaust fan in your bathroom to avoid future problems regarding water cause such as molds and stains. You should hire a contractor to analyze your wall. That's all.

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