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Which Firewood Produces the Least Ash?

Whether you have an indoor fireplace or a wood stove, odds are you have to do some ash cleanup. With my fireplace, I sometimes have to wait for up to 4 days for the coals to cool. Even then, I have to dispose of the ashes in a metal container and keep it away from combustible objects. So, is there an easier way? Is there firewood that creates less ash? Here’s what I found.

Softwoods can burn faster and leave less ash compared to hardwoods. However, softwood can leave behind more creosote buildup and increase the risk of chimney fires. Therefore, sticking to low-ash hardwoods such as oak, locust, and mulberry can keep your fire burning longer and hotter while limiting the cleanup.

So while you should stick to hardwoods, how do you know which hardwoods are best and which should you avoid? Are there any ways to make the fire burn hotter and cleaner, or tips to dispose of ash? Let’s take a further look.

Which Firewood Makes the Least Ash?

wood burning in a fireplace with ash

Even though softwoods cost about 50% less than hardwoods, it’s not recommended to be used as firewood, especially for indoor fireplaces or ovens. The amount of creosote buildup they leave behind is dangerous to health and can also catch fire if there’s too much buildup on the chimney.

Ideally, your fire should burn as hot as possible and have proper insulation. Fireplaces or ovens that have poor insulation (such as a metal or brick bottom) can lose a lot of heat and burn less efficiently. In general, the cleaner a fire burns, the less ash it creates.

When you’re ready to start your fire, choose hardwoods that are properly seasoned (dried) to get the least amount of ash buildup. Here are several low-ash hardwoods you can choose from:

  • Oak
  • Madrone
  • Black/Honey Locust
  • Mulberry
  • Hedge

Oak is one of the most popular hardwoods to use for indoor fires and it leaves behind less ash compared to other hardwoods. Mulberry and hedge can be great firewood, but they need to be very dry and the fire should be well-insulated and as hot as possible to achieve a cleaner burn.

Without a hot enough fire, parts of the wood won’t burn and it will be left behind as more ash.

Which Firewood Makes the Most Ash?

On the other hand, some firewood will produce a lot more ash than others. While some of these options make for cheaper firewood, they can generate a lot of ash and not burn or provide heat as efficiently. Here’s a list of firewood that gives off a lot of ash:

  • Elm
  • Poplar
  • Ash
  • Hickory
  • Walnut

If you are planning on using any of these woods, make sure they’re properly seasoned for at least 1 year. The moisture content of wood should be 20% or less.

Fresh, or green, firewood usually has a moisture content of 50% or more. If you do collect green firewood, store and stack it properly to help season it. Lastly, avoid burning green wood as it deposits more creosote in your stove and chimney, creating more of a health and fire hazard.

Does a Hotter Fire Make Less Ash?

Depending on your stove or fireplace setup, you might be able to make adjustments to how hot the fire is. If you increase the temperature, will the wood burn cleaner and produce less ash?

The fire’s temperature and the wood’s density are the two main factors that determine if there’s less ash created from the wood. Increasing the surface area and insulation of the fire will help it burn hotter and produce less ash. Avoid letting the coals sit on conductive materials like steel or brick.

Proper insulation is key. If your fireplace or stove has conductive materials that will steal heat from the coals, consider replacing those materials if you can. A colder fire is inefficient and can give more issues later on.

Also, ensure you’re using properly seasoned wood, as the low-moisture is key. Allow the wood to be stored for 1 year before use. Make sure it’s properly stacked and has sufficient spacing for enough ventilation.

Another way to make a fire burn hotter is to increase the surface area. This can be hard to do if you’re already running a full fire for your stove or fireplace. However, if you have the room to build a slightly bigger fire, then it might be worth it to increase the fire’s core temperature.

Lastly, make sure the fire is receiving proper oxygen. If there’s not enough ventilation, the fire can be running at a deficit and burn a smaller flame than intended.

Tips to Clean Ash

While you do want to clean ash often, leaving a 1-inch layer will help insulate your fire and make it easier to restart and maintain. As your fire is going, the more ash there is, the more the coals can be insulated and provide better heat. The coals will drop into the ash and won’t burn up for a quite a while. Although more ash can be harder to clean up, if you don’t find it a big concern, your fire could benefit from an ash layer 1-2 inches high.

When disposing of ash, it should be placed in a metal container with a tight metal lid. Since coals can be insulated and hidden inside the ash, it can stay hot for up to 4 days. Proper disposal can help prevent fires and injury. Additionally, place the metal ash container away from anything that can catch on fire or combust, including wood floors.

Lastly, avoid using a vacuum. While there are some vacuums specifically made for ashes and coals, the standard vacuum can be damaged from the hot coals and even combust, depending on the materials.

Final Thoughts

If you’re wanting your fireplace or wood-burning stove to generate less ash, choosing the right firewood, keeping your fire well insulated, and providing ventilation will help the fire run hotter and cleaner.

Choose hardwoods over softwoods due to the creosote buildup, and make sure they’re seasoned for at least 1 year prior. If your fire is burning optimally, and you use good firewood, you should be cleaning up way less ash.