What Types of Wood Should I Avoid Burning?
Which Woods NOT to Burn
The reason people buy log splitters is to have wood to build fires, either outside in a bonfire pit or inside in a fireplace or wood-burning stove.
But while the seasoned pieces of oak and maple you split with your splitter will burn wonderfully, some types of wood should never be included in your wood pile.
Below is a list of the kinds of wood you should avoid burning, along with the kinds you should be careful about using. Choose the right wood for a healthy, clean-burning fire!
Avoid: Treated/ Manufactured Wood
Often lumber is treated with chemicals to create all kinds of products:
- Coated or sealed wood
- Painted wood
- Pressure-treated wood
One problem with these chemicals is that, when burned, they can release substances that can be hazardous to human health.
The worst to burn might be lumber treated with CCA (chromated copper arsenic) to make it resistant to rot. The arsenic contained in CCA is a cancer-causing agent, which is why CCA has fallen out of general use. However, some old, discarded lumber that might be tempting to dispose of by burning it could contain CCA, making it one type of wood to keep out of your fire.
A similar warning exists for particleboard, plywood, or other kinds of manufactured wood that contain glue. One of the chemicals in wood glue is formaldehyde, which is also tied to cancer.
When burning wood, natural is best.
Avoid: Green/Wet Wood
Wood from a tree that’s been freshly chopped or felled contains moisture. When people talk about seasoning or curing wood, they’re talking about the process of leaving it outside for several months in an area with good air circulation. This dries the wood and reduces its moisture content.
Why is this important to do? Because wood that contains too much moisture (called green wood) doesn’t produce the kind of warm, roaring fire with tall flames that you might want. Instead, it results in a low, smoldering fire with long-burning embers that produces a lot of creosote.
Creosote is a fireplace’s enemy. It’s a residue formed from small, unburned particles of wood that smoke carries upward and deposits on the walls of a chimney. Too much creosote buildup, and your chimney becomes caked with a residue that can actually catch fire.
As if that danger wasn’t bad enough, burning green wood is also inefficient. Some of the heat from the flames will be used up as the moisture in the wood turns to steam and evaporates. This is heat that otherwise would be radiating outward and warming your and your friends or family around the fire.
Similar problems arise with wood that’s waterlogged. Don’t burn wet or unseasoned wood. Give your green wood time to cure instead.
Avoid: Ocean Driftwood
A type of waterlogged wood that requires special mention is driftwood, which is wood that has washed up on a shoreline. Driftwood from the ocean should never be burned in a fire.
Anyone enjoying a vacation at a seaside campsite or lodge might think that ocean driftwood could make good kindling. However, it’s been saturated with saltwater, and saltwater contains chlorine in the form of chloride. When burned along with other compounds in the wood, chlorine creates dioxin, another cancerous substance that can accumulate in the body’s tissues.
Ocean driftwood is especially dangerous to burn in an enclosed structure like a fireplace or wood stove, but for safety reasons, many seaside communities prohibit people from burning it anywhere.
Avoid: Poison Ivy
Plants like poison ivy, poison oak, and poison sumac aren’t harvested for their wood. However, while cleaning up your property, you might be tempted to add any stems you find into your pile of wood to burn.
Don’t do it.
Urushiol, the substance on the leaves, stems, and roots of these plants that causes a rash if touched, also can cause severe irritation and an allergic reaction in the tissues of the lungs if inhaled via smoke.
If you have inhaled smoke from burning poison ivy, poison oak, or poison sumac, get medical care immediately. But to avoid those problems, avoid burning any of these woodland plants to begin with.
Caution: Wood from Conifers
Pine, fir, and spruce: cone-bearing trees make for a beautiful sight in the forest, but their wood shouldn’t make up the bulk of your firewood pile, especially for indoor fires.
Beneath their bark, conifers have a sticky, protective substance called pitch or resin that you won’t find in trees like oak or maple. Resin doesn't directly burn off and build up as creosote. Instead, according to outdoor professionals, it seems to make it easier for wood to burn before it's been properly seasoned, which is why pine and other woods from conifers are associated with creosote.
Additionally, woods that contain a lot of resin tend to crackle and let sparks fly from the fireplace, making them potentially dangerous to use as your only indoor wood source.
However, because resin is extremely flammable, woods like pine are a great choice to use as kindling, the smaller pieces of wood that help get a fire going. Use a little bit of conifer wood in your outdoor fire to transfer the heat and flames from tinder to your main pieces of firewood.
Caution: Artificial Wax Logs
These days, you can find artificial logs for sale even at grocery and convenience stores. These logs are made with sawdust held together with wax—and they’re not logs made for burning in a small chamber.
The reason is that the wax in these logs burns at such a high temperature that it risks setting the fireplace insert, wood stove, or other enclosed structure on fire.
If you want to burn an artificial log inside an enclosed space, look for one that’s made of 100% compressed sawdust, and save the logs that contain wax for your outdoor campfires or open hearth fireplaces.
Bonus: Diseased/Pest-Damaged Wood
You might wonder if it’s safe to burn wood from trees that have been destroyed by diseases or pests. After all, the logic might go, if dangerous chemicals can be released when wood is burned, why not a fungus spore?
The good news is that plant diseases work differently, and fire is one of the best tools for getting rid of diseased wood. In fact, some arborists and university extension professionals recommend felling and splitting diseased trees first for your firewood!
Using a weakened tree for firewood removes a tree that could be in danger of falling and causing harm. It also helps thin out a grove so that healthy trees have more room to flourish.
However, there are some caveats not with burning such wood, but with storing and transporting it:
- If using ash that’s been attacked by the emerald ash borer, don’t transport your firewood off the property. You risk spreading the ash borer larvae, which live beneath the bark and are hard to see—and are extremely destructive.
- If using oak that’s been affected by oak wilt disease, don’t store your logs near other oak trees. Oak wilt is a fungus that can spread easily.
Building the Right Fire
Once you’ve chosen the right kind of wood for burning, you’re almost ready to start your fire:
- Clear your stove, fireplace, or fire pit of waste and debris
- If outside, set up far away from branches, grass, and other material that can catch fire
- Have a bucket of water or another method of extinguishing a fire nearby
With the right type of firewood, you’ll be able to build a fire that’s safe for everyone to enjoy.