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Controlling Mold Growth in Garage

cyarsev | Posted in General Questions on

Hello, looking for some advice on a moldy garage.  House is near Glens Falls, NY (zone 6A).  Garage is uninsulated, very airy (i.e. not tight construction by any means) with a poured cement slab.  With the non-stop rain this summer, I noticed boots and bags in the garage have mold growing on them.  Especially if they were worn before (dirty or sweaty).  This summer was very wet, with lots of humid nights and not real hot days.

I have read just running a fan at night can help (when dew points and temps are lower).  Or should I be installing a vent fan, venting to the outside?  With the non-insulated construction it seems just running any fan inside the garage will probably create ventilation through all the cracks/leaks.

Finally, should I put something over the cement to act a vapor barrier.  With this occurring in the summer, this seems less likely of an issue, as I believe vapor issues through slabs are more of an issue in colder temps.



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  1. user-2310254 | | #1


    If the garage is unconditioned and conditions are humid, you're bound to have mold growth on some surfaces. It's possible you could air seal and insulate the structure and add an HVAC system or dehumidifier, but would all that expense and effort be worthwhile?

  2. cyarsev | | #2

    Definitely not worth air sealing, insulating, and adding HVAC or dehumidifier. It's just a garage used for storage. I have thought of just blowing in insulation, as the dry wall is already up.

    Would moving air around with a fan help at all? Maybe set a timer so it only runs at night for 8 hrs?

  3. GBA Editor
    Kiley Jacques | | #3

    Having belongings ruined from mold (I can relate) seems reason enough to consider a few low-tech measures. Maybe use an IR camera to locate the biggest air leaks (the door and any windows will be among them), and do a little strategic canned foam spraying or poly stapling, if feasible. Then add an Energy Star-rated (economical over the long term) dehumidifier set to 50. I've taken these steps and have seen an improvement in my basement. Just a thought.

  4. user-2310254 | | #4

    I agree with Kiley. If the garage is attached to the house, it would make sense to install a fan that would run for 15 minutes whenever a vehicle is parked (assuming it has an ICE and is not an EV).

  5. cyarsev | | #5

    What is an ICE?

  6. kyle_r | | #6

    Internal combustion engine

  7. Jon_R | | #7

    I run a fan in the garage when there is something wet in it. This does dry the thing quicker.

    Ideally, I'd have a well air sealed garage and could dehumidify it. Less rust on cars alone would probably make this cost effective.

  8. cyarsev | | #8

    There are no cars in the garage, so no fumes or wet cars to ride about. Just trying to aid in drying it out. What about the cement floor? Should I seal it? Or put down a barrier?

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