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  1. #1
    Join Date
    Jul 2012
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    Mold Around AC Ducts in Garage

    Hi everyone,

    I was glad to find this forum and have read a few responses to similar issues regarding mold around AC ducts. I recently discovered mold growing around my AC ducts in the garage and wanted to see if anyone here would be able to confirm that it is indeed mold and what some of the initial/next steps I should take to remove/repair. Since buying the house 2 years ago, I haven't done any major AC repair work except vacuuming/cleaning out a clogged drain pipe coming out of the unit. I have two children and am worried that the newly growing mold might cause them to get sick. Especially since I live in Florida and we will most likely be using AC until the end of time

    Any help would be greatly appreciated!

  2. #2
    Join Date
    Jan 2009
    Location
    SE Iowa
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    It looks just external to the unit where the unit has been sweating for a long time due to condensation from inadequate insulation. I wouldn't worry too much. Hit it with bleach and add more insulation so the surface temp stays below the dewpoint of the air in the attic.

    You might want to make sure you have adequate airflow too. Cold plenums can be caused by too low of airflow.

  3. #3
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    Jul 2012
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    Thread Starter
    Ah ok, that makes sense. What would be a better insulation method? I noticed its growing only on what looks like joint compound. And I found a poorly closed bucket of compound in my garage last week which had the same type of mold growing on it.

  4. #4
    Join Date
    Jan 2009
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    SE Iowa
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    I think that's mastic on the ductwork, not a joint compound. TO insulate it, typically you use a foil faced fiberglass designed for use on ductwork. You would just go ahead and insulate the whole exterior of the plenum. Otherwise, there are some neoprene insulation material that can be used, but that's more for commercial applications.

  5. #5
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    Jul 2012
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    Thread Starter
    Sounds good, thanks for providing some much needed info. Looks I have some cleaning to do!

  6. #6
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    Get a closed cell adhesive backed foam 3/8" thick. Apply over the cleaned area where mold grew. Avoid any insulation that the moisture in the space could penetrate.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  7. #7
    Join Date
    Sep 2009
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    You like to keep it in 68* don't yah?

  8. #8
    Join Date
    Jul 2012
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    Thread Starter
    Thanks TB. And nope, actually it's usually always set to 78*.

  9. #9
    Join Date
    Sep 2009
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    Open up that unit you will see more mold inside. Don't use no bleach though...

  10. #10
    Join Date
    Mar 2005
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    997
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    Yes you will need to treat the mold inside as well

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