Does Firewood Ever Go Bad?


Whenever I have a huge supply of firewood on hand I often wonder if I’ll ever make it through the pile. I recently cut down 11 massive oak trees and boy does that look like a lot of wood. It will take years to burn though it all going through 2-3 cords of wood per winter.

I would hate for it all that wood to go to waste, so I had to ask myself a simple question. Does firewood ever go bad?

Properly stacked/covered firewood won’t get to the point where it won’t burn, but it will continue to go through the natural decomposition process slowly drying out. If it’s kept dry and properly stacked the wood should last for decades before it starts to rot away. Let the wood get soaked in the rain/snow and it will rot away in a single winter.

You’re the only person that can dictate how long your wood will last. Continue reading to learn the right way to stack and cover wood to prevent premature decomposition.

What Causes Wood To Go Bad? (Dealing With Wood Rot)

Firewood ages differently than most other living things. It doesn’t really go bad in the traditional sense. There are two extremes that can happen as firewood goes through the natural degradation process. Properly stacked and seasoned wood will slowly dry out to the point where it lights up hot and burns way too fast. Wood that’s left out in the elements exposed to water will quickly rot away and turn into compost.

Firewood that’s gone “bad” usually refers to wood that’s decomposing and starting to rot away. This is the natural process where wet wood slowly gets softer and goes back into the soil. As the wood starts to rot away you’ll notice it goes from green to gray and finally to dark brown.

The wood will get softer and eventually crumble into pieces in your hand that look like soil. If you find a piece of rotten decaying wood in your wood pile it usually means that you need to find a way to control moisture.

You can still burn rotten firewood, but since the woods wet it will smoke and smolder in the fire. There’s a certain point where it’s best to get rid of it.

Firewood Never Gets Too Old to Burn

Firewood will never get too old to burn if you keep it dry. Think about some of the old barns that are still hanging around out in the countryside. Some of those barns have been standing for hundreds of years and they’re still perfectly sturdy.

So how did they keep the barn standing when all the barns around it needed to be replaced. They paid attention to leaks and kept moisture at bay. I’m sure that there was some luck involved too, because a 100 year old barn will go up in flames fast.

It’s kind of crazy, but if you kept firewood dry and bug free it would probably outlast you. Problems only start to arise when the wood gets wet which speeds up the degradation process.

Keep An Eye On The Moisture Level

Moisture is by far the biggest enemy of firewood. A few months exposed to the elements will take years out of the lifespan of your wood. Make sure it’s raised off the ground on a rack or pallet and covered up. A tarp draped over the top is all you need.

When a trees first cut down the moisture level will be in the 35-45 percent range. That’s a ridiculous amount of water that needs to slowly drain out of the wood. You need to get down under the 20% range (10-15 percent is optimal) for wood to start burning well. Under 20% is when the wood is easy-ish to light and stays lit for a while.

Once your wood gets water logged and goes up over the 50% range it will quickly start to rot away and turn back into compost. It will basically turn back into the dirt after about 6 months to a year of water exposure. I recommend picking up a cheap moisture level meter if you’re interested in checking your firewood. It’s really nice to be able to check a log and see if it will be easy to light when trying to start a fire.

Can You Burn Dead Rotten Wood?

Yes you should be able to burn rotten wood regardless of how bad it looks. Rotten wood won’t make you sick or anything. It just won’t burn right since the moisture content is so high. The wood will burn at a low temperature so it can’t reach complete combustion.

You’ll end up with a cold smoldering fire, that produces a lot of smoke, and ash/creosote. Keep an eye on the creosote levels in your chimney, because rotten wood can be very dirty. Whether or not you should burn or put the wood out for compost is up to you.

The wood in the picture above is right on the edge of where I’d say to let it compost. At that point I would probably go with one last campfire to burn through it all and replace it with the good stuff.

When and Where Should I Throw Away Rotten Wood?

When it comes to rotten wood, I live by a simple rule. If I can pick the log up without it breaking apart in my hand, it goes in the wood burner or firepit. My wife probably hates that rule since I end up leaving a trail of wood crumbs in the living room for her to clean up, but I’m trying to get better.

So what should I do If the wood crumbles and breaks apart as I try to pick it up. That’s the point where the wood needs to be disposed of and go back into the earth. I usually toss the decayed wood back into the forest to compost on its own. It will usually be gone and completely rotted away by the end of winter.

You might want to check out my post describing what you should do with rotten wood. I give a few more tips for people that can’t just toss wood into the forest like me.

What If My Wood is Moldy or Fungus Covered?

Firewood that’s covered in mold and fungus is a telltale sign of wood that’s been left out in the elements. Mold/fungus needs lots of water to survive, so the wood couldn’t have been covered and was probably left sitting on the ground. I’ll go over the easiest/best way to season firewood in the following section. Seasoning wood really isn’t hard once you understand a few basic points.

Is it safe to burn moldy wood or wood that’s covered in fungus? The only time you shouldn’t burn moldy and fungus covered wood is if you have asthma, severe allergies, or another respiratory problem. Spores will be released into the air as the wood burns which can cause issues with your sinuses.

You probably shouldn’t store moldy/fungus wood inside for the same exact reason. I wouldn’t want those spores to be released into my living environment. That’s asking for it to spread onto your drywall and wall joists. Play it safe and separate the good and bad wood.

Wood that looks like it has mold/fungus should only go inside for a few hours as you plan on burning it. An even better idea would be to burn it in a campfire.

Seasoning Firewood To Stop it From Rotting

Seasoning firewood doesn’t have to be complicated. All you need to do is understand the four key factors needed for drying out wood. You need to get the wood up off the ground, cover up the top, leave the sides open for airflow, and setup the stack in a sunny location. Don’t worry about rot if you follow all four of these suggestions.

  • Get Wood Off The Ground: Build or buy some type of firewood rack to get the wood up off the ground. This allows air to flow across the bottom rows and keeps your wood out of pooling water and most of the snow. I recommend purchasing firewood rack brackets (my favorite) and a few 2x4s to build a nice rack. You can screw the rack together in under 5 minutes and replace the boards every 5-10 years when they start to look bad.
  • Cover Up The Top: Cover up the top of your wood to reduce water exposure. A little bit of rain won’t destroy your wood, but prolonged water exposure will lead to rot. Leaves are another culprit that will quickly destroy a wood pile. They sit on the top of the pile and trap in moisture eating away at the wood.
  • Promote Airflow By Leaving Sides Open: Leave the sides of your firewood rack open to increase the airflow through the wood. Proper airflow significantly speeds up the seasoning process. If you plan on covering the wood with a tarp only drape it up over the top. The little bit of rain that lands on the sides of your logs will be dry in a matter of days.
  • Increase Sunlight: How much sunlight your firewood rack will get is largely dependent on your yard setup. Try to give your wood as much sunlight as possible without sacrificing convenience. I recommend placing your wood pile within 30 feet of your main door, but don’t stack firewood against the house.

How Long Can I Store Firewood?

You can store firewood for decades if you limit moisture and work to keep insects and other pests at bay. Realistically I like to use my wood within the first 2-3 years, because it gets a little dry after that. The first 6 months is spent seasoning and then you have 3 winters to burn through the wood. I try to cycle out the old wood and replace it with new as I continue to split logs.

Firewood never really gets too dry, but it will start to burn really hot and fast. After 3 years the moisture level will drop below the optimal 10-15 percent range. It goes up like a tinderbox once it gets down to about 8 percent. You can buy a cheap moisture meter if you want to see how the firewood is progressing through the seasoning process.

Watch Out For Insects (Carpenter Ants and Termites)

Try to inspect your wood for insects every once in a while. Termite and carpenter ants can do just as much, if not more, damage than water rot. Look at the picture of termite infested wood in the picture above. They can make quick work of a log when they’re munching away at it.

Insects are one of the main reasons why experts recommend keeping firewood out of the garage and away from your house. They can cause serious damage to the structure and wall framing in your house. I spray my firewood with a boric acid based insecticide (Zap-a-roach) when I occasionally see ants and termites. Boric acid based insecticides are completely non-toxic to humans and pets unlike traditional insecticides.

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