Can You Burn Moldy Wood?


If you burn a lot of firewood, there’s a good chance you’ll run into some moldy wood eventually. A little bit of mold on a stack of wood is pretty common. A wet natural food source is a pretty reasonable place for mold to grow. You can obviously light moldy wood on fire, but does it pose a health risk? Can you burn moldy wood safely?

Burning moldy wood releases mold spores into the air which can be dangerous for people with asthma, allergies and other breathing problems. I can give the blanket recommendation to never burn moldy wood, but burning moldy wood outside isn’t a concern for most healthy people. Just don’t burn or store the wood inside because you don’t want to introduce mold spores to your house.

Whether or not you should burn moldy wood depends on your overall health. I wouldn’t recommend seeking moldy wood for a camp fire, but it won’t bother most people at an outside campfire. There are a few rare toxic molds that I’ll get into later. Keep reading to find out a few ways to deal with moldy firewood.

Should You Burn Moldy Firewood?

Mold is a very common problem with firewood. Conditions outdoors are damp and firewood has lots of nutrients that mold needs to grow. It’s the perfect breathing ground for mold and fungus. There are ways to prevent mold that I’ll get into later, but lets start off by asking a simple question. Should you burn moldy firewood?

While I obviously wouldn’t recommend seeking out moldy firewood it’s generally safe to burn outside. That’s assuming that you don’t have breathing problems and allergies to mold. Just keep in mind that burning mold will release mold spores into the air. Mold spores are everywhere so that’s not terrible by itself, but it can cause breathing issues in people with certain medical conditions.

Whether or not you’re willing to take that risk is up to you. You can always set the moldy wood off to the side and wait for it to die. Just make sure the rest of your pile is properly covered, because usually grows in wet environments. That’s not what you want when trying to season firewood.

The mold should die off if you leave the wood to dry for about 6 months. You can always spray it with some liquid bleach to speed up the process. Bleach decomposes within a day or two when exposed to the sun so burning it is completely safe.

Is It Safe To Burn Moldy Wood?

As I mentioned above, burning moldy wood is safe for most healthy people. People with severe allergies, asthma and other breathing problems might want to avoid it. Think about the fact that mold needs a wet environment to grow. Burning wet moldy wood will result in lots of black smoke, which is bad for people with breathing problems anyway.

There is one thing that you need to watch out for. Never bring moldy wood inside your house. Storing and burning moldy wood will introduce mold spores into your home. A good HEPA air filter will help, but mold spores can cause serious problems with people that have allergies.

There Are Toxic Molds

Up until this point I was assuming that we’re not dealing with toxic molds. Toxic molds are very rare, but it’s still possible for them to infect your wood pile. Black mold is the most common toxic mold that you’ll have to deal with.

There’s a major problem with identifying toxic molds. They look almost identical to non-toxic common molds by visual inspection alone. Technically it’s best to air on the side of caution, but you can do whatever you want. It’s not worth burning mold inside, but outside usually won’t cause problems.

Preventing Mold On Firewood

Preventing moldy firewood is surprisingly easy when you understand what mold needs to survive. Mold needs a fuel source, water, and it prefers dark areas with very little airflow. They get the fuel from the wood, but increasing airflow and reducing moisture will significantly reduce mold buildup. Throw in some natural sunlight and the mold has no chance of survival.

  • Get Firewood Off The Ground: Stack your firewood on pallets, 2×4’s or a firewood rack to get it up off the ground. I really like the cheap firewood rack brackets you can get on Amazon. It takes like 5 minutes to build the rack and it will be sturdier than the cheap metal racks. Plus you can always replace the 2×4’s after 5-10 years and it’s like you have a new rack.
  • Cover Up The Top: You can use a firewood rack cover (my favorite) if you’ve bought a commercial rack. With a larger pile you’ll want to cover up the top with a tarp making sure the sides are exposed or build a small wood shed like the one in the picture above.
  • Leave The Sides Open For Airflow: Leaving the sides open for airflow is especially important when covering your wood pile with a tarp. It allows wind to blow through the wood pile and the sun will dry the wet ends in 2-3 days after a rain storm.
  • Get Lots of Sunlight: Mold will never grow in a sunny area. Lots of sun usually means very little water buildup.

Separate The Moldy Wood and Give It Time to Die

So what if you’re wood already has mold on it? A little bit of mold isn’t that big of a deal. It’s actually extremely common. Just separate the wood from the rest of the pile so it doesn’t spread.

Stack the moldy wood in a sunny area making sure you get it up off the ground. The mold should die after a few months, but you can always speed up the process by spraying it with bleach. Bleach will kill mold fast and disintegrates when exposed to sunlights.

Don’t Burn or Store Moldy Wood Inside

I briefly mentioned this above, but you don’t want to introduce mold spores into your house. Mold can cause serious breathing issues when you’re exposed to it on a day to day basis. You probably won’t even notice the slight breathing change until all of a sudden you can’t breathe.

To make matters worse, mold can be very hard to find and kill. The spores can easily jump from your firewood pile back into your drywall and wood joists. Hiring a mold elimination service is very expensive so do everything you can to avoid bringing it inside.

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