I live in Houston and have a house that was built in 2013. Just yesterday my wife noticed some surface mold forming in my daughter's closet at the ceiling. Upon further inspection of the rest of the house, every single closet has this surface mold at the ceiling. You can easily just wipe it off but figured it was a humidity issue.

I bought a humidity gauge and the main areas of the house are around 55% but near the ceilings of the closets are at 85%!

I have a buddy in the AC business that's going to send a tech out. So I checked the AC and the condensate line is completely clogged and has been draining through the emergency line.

I checked the entire attic and no signs of mold / leaks in the attic.

What could be the cause of this and how do I fix!?!?

is this around the air register?

No it's in all the closets and none of them have air vents. Just solid ceiling

Clean the main drain line and put an ounce of bleach down the clean/out tee every March as a preventative.

Often when the coil does not drain well you will end up with higher humidity in the house as the coil stays wetter.


What size are the closets ? Are they walk in ? Or like little 2x4 sizes ?


For the mildew/ mold get some concrobium and take a rag and or spray and wipe the ceilings with it.

https://www.homedepot.com/p/Concrobium-32-oz-Mold-Control-25326CAL/310228466

HoustonAg12 said:

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No it's in all the closets and none of them have air vents. Just solid ceiling

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I don't think you have a problem so much as a science confirmation.

Houston is humid. Are your closets closed? If so...stop doing that. They don't always have air registers and you are just bottling up a room with no circulation and humidity is soaking down through the ceiling, possibly through the drywall or light fixtures if present.

Open them up, let them dry, leave them that way.

By no means am I an expert, but it seems water vapor shouldn't be moving down through the ceiling drywall, unless there's also a problem with ventilation in the attic. All that hot humid air in the attic should be going out through roof vents.