Why are my metal floor vents sweating and growing mold?
High humidity and unsealed gaps around metal floor registers allow moist crawlspace air to enter the home, causing the cold metal vents to sweat heavily and grow mold. This leaves homeowners dealing with unsightly black mold around the floor grates and white buildup inside the vents, which requires sealing the gaps to stop the airflow.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Using foil tape to seal gaps around the registers and prevent pulling in crawlspace air
- 2Insulating the registers
- 3Spraying a mild bleach solution on the register to wipe up the growth
- 4Running a dehumidifier to control indoor humidity
- 5Texted the landlord and waiting for a response
- 6Changing the air filter every month
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“Registers are metal and ghost sweating like it’s their full time job and growing mold ( that I just found )”source ↗
“I was told by Google to foil tape these to seal them and keep them from sucking the crawlspace air in. Is this an acceptable solution to my problem?”source ↗
“can anybody tell me what this indicates? my understanding is a few years back the previous owner of this place had the inside of the ducts sprayed with kilz, which doesn't sound very useful but then again I'm naive about HVAC. I had the mold tested and it came back as not the super toxic stuff but I can't help feel like this can't be good. I live in Houston where it is quite humid outdoors all the time.”source ↗
Where this came up
People with this problem also raised
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- 7How to clean mold on furniture after rain gets inside
- 7How to get rid of severe black mold on bathroom grout
- 2Why is there condensation and damp spots on walls only on laundry days?
- 7Why does my house smell like cat urine when there is no visible mess?