Moldy Firewood

Asked January 11, 2021, 9:39 PM EST

Hello! This year I was very excited to have a wood-burning fireplace and have been acquiring and splitting rounds as well as collecting other free firewood to stock up. I stacked the wood in my garage, trying to leave a gap between the wood and the wall to allow some air flow. It looks like the wet wood in the cool garage has resulted in mold :( Looking online, I’ve found advice to stack wood outside (for a few reasons). Is this the best course of action? Should I never stack firewood in my garage? For my wood that is already moldy, is there anything I can do to get rid of the mold? Also, if I stack it outside, any tips? I’m getting a firewood rack so it’s raised up off the ground and I’m planning on putting a tarp over the top to protect it from rain. Mine will most likely just have the tarp on top for rain protection, though. Is that enough protection from the rain? Any advice you can give would be much appreciated!

Washington County Oregon

5 Responses

Thank you for your question. It raises several concerns that you should be aware of, particularly because the mold you see on the outside may be small, compared to that beneath the bark. First, depending upon the species of wood you are burning, fungal spores may be released into indoor air, causing allergic reactions in humans--potentially life threatening. Second, wood decaying (naturally) by decomposition may harbor insects which pose a threat to fiber inside your home. Do not store wood in any indoor structure, even if heated. Here are recommendations from various Extension articles: bring no firewood in until immediately before burning. Leave unburned logs outside on a metal carrier that promotes circular airflow, and keep logs apart. Resources disagree about covering with tarps, particularly since rain may decrease proliferation of some fungi. A covered structure, such as a lean to, or open shed, would be safer. Finally, do not treat with fungicides, some of which can be dangerous when inhaled. Good luck!

Thank you so much! I will work on getting it outside on a metal carrier as soon as possible. Regarding the existing mold, will it die off once I get it outside and it’s got better air flow and exposure to heat from the sun? Or should I wipe it off or remove it in any way? Thank you!

The external molds will decompose, but not quickly. That takes heat and full sunlight. None due in the foreseeable future. There is no method to eliminate internal mold. Can you let this wood dry out this winter, and use Presto logs until next winter?

I can definitely let it dry out this winter! Is there any point in trying to separate out pieces that don't appear to have mold on them yet and trying to use them for firewood, or should I just keep all the wood in the stack together and let it all dry out?

The more you can separate and dry the individual pieces of wood, the better. You will not be able to tell if there is a mold growing inside the logs, though, so that risk remains.