How To Get Rid Of Mold On Firewood

Mold can become a serious problem with improperly stored firewood. Damp firewood is the perfect breeding ground for mold. Luckily killing mold is easy with a little bit of time and proper firewood storage. How do you kill mold on firewood?

The best way to kill mold on firewood is to stack and store it properly. You have to dry the wood out so there’s no moisture for mold to grow. After a few months of sunny storage your firewood should be mold free and ready to burn.

What if I already have mold on my wood? Is it too late to kill the mold? Don’t Worry! Your firewood isn’t destroyed just because of a little mold. With proper storage and a little prep work, your firewood will be mold free in no time. The following guide should help kill off all the mold before it becomes a problem.

How To Get Mold Off Firewood

Let’s start off by saying that it’s generally safe to burn moldy firewood, but bringing it into your house can cause serious problems. You don’t want to store firewood inside and release spores into the air. This can cause breathing problems and lead to mold growth in the house.

Not being able to store moldy wood inside can be a serious pain so you should work on preventing and killing mold before winter approaches. So what do I need to do to prevent mold growth?

  • Sunlight: Sunlight is the number one enemy of mold. There’s no stronger heat source than the sun! Maximizing sunlight will speed up the drying process and without moisture there’s no chance of mold growth. Exposing mold covered wood to direct sunlight will kill mold fast.
  • Seasoning Firewood: Mold is caused by excess moisture in your firewood. Seasoning firewood is another name for drying it out, which will reduce the chance of mold. You need to properly split, stack, ventilate, and cover your firewood to speed up the seasoning process. Firewood that’s properly stacked should season in 6-12 months depending on when you cut it. Cutting early in the spring will give you enough time to season the wood before winter.
  • Properly Stacking Wood: There are three steps to properly stacking your firewood. You need to find/build a rack to get the wood up off the ground. Cover up the top of your wood to prevent snow and leaves from building up on the wood. Leave the sides of your firewood open to increase air circulation and speed up the drying process. A light breeze more than makes up for a day of pouring rain. It only takes a few hours to dry firewood that’s been rained on.

Properly seasoning your firewood is the best way to kill off mold and improve the efficiency of your firewood. Mold is the result of excess moisture and improper storage. If there’s mold on your wood it will be hard to light and smoke like crazy. So it’s in your best interest to kill off the mold by going through the drying/seasoning process.

How To Prevent and Remove Mold From Firewood

Properly splitting, stacking, ventilating and covering your firewood is the easiest way to prevent mold growth. This is known as the seasoning or drying process. Mold needs moisture to grow and by removing that moisture you’re making the wood pile an inhabitable environment. Mold that’s on the firewood will die off and there won’t be an opportunity for fresh mold to grow.

Preventing mold growth should always be your first step, but sometimes you’ll have to find ways to kill and remove mold from firewood. Don’t waste your time spraying bleach and other chemicals on your wood. There’s no magic chemical solution. Sunlight, ventilation, and removing moisture is the key to killing mold on firewood.

All you need is a little bit of time and enough sunlight/wind to dry the wood. Direct sunlight will kill mold fast! A week of direct sunlight is a surefire way to kill off mold growth. Properly stacking and covering your firewood is usually all it takes, but you may need to remove problematic firewood from the stack and take it to a sunnier area.

Before I explain how to prevent and remove mold from firewood, let’s answer a simple question.

Does Fire Kill Mold On Wood and Is Moldy Firewood Bad?

Fire will kill surface mold on wood, but it will release mold spores into the air. So can you burn moldy firewood? Burning moldy firewood isn’t a big deal outside, unless you have allergies/asthma, but it can cause major problems in your house.

Mold spores will release into the air in your house and infect your living area. It increases the chance of mold growing on your walls, furniture, carpet, etc. and can cause serious breathing issues. Even people that don’t have allergies and asthma can have issues breathing in a mold spore infested house. So you should always try to find a way to kill and prevent mold growth before winter comes.

Building or Buying A Simple Firewood Will Prevent Moldy Firewood

Building/buying a cheap firewood rack will solve 99% of the problem. I’ll go into the complete seasoning process below. Your goal is to get the wood up off the ground, cover the top row, and leave the sides exposed. A simple rack with a tarp on top is all you really need.

Don’t buy one of those metal racks you see in the store. They’re way too small and will rot out in like 3 years. You’re better off building a rack like the one pictured above. Personally I’ve switched over to buying firewood bracket kits that you use with 2x4s. It’s so much easier to swap out boards every 5-10 years and they can be taken apart with a few screws for transport.

You’ll want to toss a tarp up over the top of your rack to keep snow and leaves from resting on the wood. Leaves are the biggest problem since they get wet and trap water for months at a time.

Stacking Firewood To Kill Mold

Let’s start off by saying it doesn’t matter if you’re starting with a fresh cut pile of wood or dealing with old moldy junk. You always go through the same process to dry out and season firewood. It should all dry with a few months of proper storage.

The only wood you’ll want to toss is old rotten out logs that are falling apart. Rotten wood is safe to burn, but it’s gone through the decaying process so all the usable energies gone. You’ll end up with a smoky fire that doesn’t put off much heat. I go by a simple rule when it comes to assessing rotten wood. It goes in the fire if it’s sturdy enough to be picked up without crumbling apart.

How do you store and season firewood to prevent mold? It’s all about increasing sunlight and airflow while trying to reduce moisture. You’d be surprised how easy it is once you understand the basics. There’s really no way to completely screw up if the woods up off the ground, covered, and given airflow.

Step 1: Sunlight Kills Mold Fast

Find a nice sunny spot for your firewood pile. You want to store the wood close enough to the house so it’s easy to get in the winter and far enough away to keep ants, termites and other insects away from your house. I usually look for a spot at least 20ft away from my door.

Avoid wet shady spots and try to get as much sun/wind as possible. Increasing wind and sunlight will significantly speed up the seasoning process.

Step 2: Lifting Firewood Off The Ground Prevents Mold

Getting your wood up off the ground will increase airflow to the lower rows and prevent moisture problems that lead to rot. It should also reduce the risk of getting an insect infestation. Here’s a simple tip: You can kill off most insects with borax, water, and sugar.

Even properly stacked firewood will have moisture problems if it’s stacked directly on the ground. The top 2 ft will be well seasoned, but the bottom will get mold growth and quickly rot. Do yourself a favor and find some way to get your wood up off the ground.

Stacking your wood up on pallets is by far the cheapest way to get it up off the ground. The pallets should last 5-10 years since they’re designed to withstand moisture. A pallet is 48″x40″ so it’s the perfect size for storing firewood. You’ll get 2 rows per pallet and you can really stack up wood with a solid base.

Step 3: Stacking Wood Improves Airflow and Reduces Water Buildup

Firewood won’t season in a pile so stack it up right after you finish cutting/splitting. Wood won’t start drying out until it’s split into smaller pieces so split it fast so it can season before winter. You’ll need a few warm months to properly season firewood.

Stack the wood so that it’s a maximum of 2 rows deep. One row is better, but it’s hard to find space if you’re storing a lot of wood. Keep the wood 4-6 foot tall for safety purposes. You’ll want to keep the pile shorter if kids will be fetching wood.

Step 4: Cover The Top and Leave Sides Open

Cover up the top of your wood so wet leaves and snow don’t settle on the pile. Snow usually melts in a few weeks, but wet leaves can stay on your pile for years. A small 6×8 tarp is the perfect size for most wood piles. It’s big enough to drape over the top without covering up the sides.

You want to make sure the sides are left open to promote airflow and allow sunlight to hit the wood. The ends of your wood will get a little wet, but the sun/airflow more than make up for it. It won’t take long to dry out the ends.

Step 5: Seasoning Firewood Reduces The Risk Of Mold

Most people say to wait at least 6 months before burning it but that’s usually overkill. It might take 6 months to season wood in cold/wet weather, but 3-4 months is usually enough in the summer(dense wood can take longer). Give the wood a little extra time if there’s mold growth. That usually means your starting with an unusually high moisture content.

Is It Safe To Burn Moldy Wood?

Burning moldy wood probably won’t kill you, but it’s not a great idea to bring it inside your house. The real problem with moldy firewood is when people bring it inside for storage before using it. This allows the mold spores to release into the air and spread throughout your home.

You can usually get away with burning mold if it goes straight in your burner. The mold spores won’t have a chance to invade your home since they’ll burn off within a minute or two. Most of the spores will burn off and head up through the chimney.

You might want to avoid burning moldy wood if you have asthma or bad allergies. Burning mold can exasperate the issue and cause short term breathing problems. Check out my post explaining a few more safety tips for burning moldy wood for more info.

Can I Burn Moldy Wood Outside?

Burning moldy wood outside shouldn’t be a problem. I usually save up all my garbage wood to burn up during the summer. This is usually a combination of mold, rot, and insect covered wood. Anything that I’d rather not bring into the house gets tossed in the firering during the summer.

Once again you might have to take precautions around people with allergies/asthma. Wait until the fires going strong before tossing on the moldy wood because you’re probably dealing with moisture issues that will cause lots of smoke.