All wood burns, but not all woods burn the same. Some burn hotter, slower, and cleaner than others. Some smoke a lot, and some have a lot of sap or resin that clogs your chimney quickly. Therefore, the best types of firewood for a wood stove or fireplace burn hot and relatively steadily, producing more heat and, typically, burning more completely. These woods tend to be hardwoods, such as hickory or ash, rather than softwoods, such as pine and cedar.
Hardwoods such as maple, oak, ash, birch, and most fruit trees are the best burning woods that will give you a hotter and longer burn time. These woods have the least pitch and sap and are generally cleaner to handle. However, hardwoods are generally more expensive than softwoods and are more prone to leave clinkers, a hard and stony residue, in the leftover ash.
If you're burning birch firewood, be aware of the thick inner brown bark called the phloem. This bark retains a lot of moisture and can prevent the wood from drying evenly. Therefore, it is best to mix birch with another type of hardwood for a cleaner burn and less smoke. Smoke leads to a buildup of creosote, which is a byproduct of wood combustion consisting mainly of tar that commonly causes chimney fires.
Softwood is the cheapest type of wood you can buy. Fir is the best choice, but other softwoods include pine, balsam, spruce, cedar, tamarack, alder, and poplar. Softwoods tend to burn faster and leave finer ash compared to hardwoods. They also can be messy to handle, especially pine, spruce, and balsam, as they cause creosote to build up more quickly in your chimney.
Comparing Firewood by Heat Energy
Different firewoods can be categorized by the amount of heat energy they create per cord of wood. The best firewoods offer the heat-energy equivalent of 200 to 250 gallons of fuel oil. These include the following:
- Beech (American)
- Birch (Yellow)
- Hickory (Shagbark)
- Maple (Sugar)
- Red oak
- White ash
- White oak
The next category of heat energy is the equivalent of 150 to 200 gallons of fuel per cord of firewood. These woods include:
- Birch (White)
- Cherry (Black)
- Douglas fir
- Elm (American)
- Maple (Red and Silver)
In the lowest heat-energy category, each cord of wood produces about the same heat as 100 to 150 gallons of fuel oil:
- Alder (Red)
- Cedar (Red)
- Pine (Lodgepole and White)
- Spruce (Sitka)
Make Sure Your Wood Is Dry
You should never burn "green," or insufficiently dried, wood as it produces less heat and more smoke (and, ultimately, creosote) than properly dried, or seasoned, wood. For proper storage, you should stack your wood for efficient air circulation, covered at the top only, and make sure it is thoroughly dry before burning. A good rule of thumb is to rotate your firewood, as in burning the older dryer wood first, to avoid wood rot and waste.
Wood should have a moisture content of only 15 to 25 percent for burning. With the moisture above 25 percent, wood is hard to start and burns poorly and inefficiently, creating excessive amounts of water vapor and smoke.
Woods to Avoid
Salvaged firewood or other scraps can save you a lot of money when it comes to heating your home with wood. But there are certain wood products and other items that you should avoid for health and safety reasons. Many of these will produce hazardous fumes indoors, as well as chimney emissions that would be an environmental concern. Some also pose additional risks to your stove metals or can create a hazardous buildup of creosote in your chimney.
For your safety you should always avoid burning:
- Painted or varnished wood, trim, or other wood by-products
- Pressure-treated lumber
- Engineered sheet goods, such as plywood, particleboard, and MDF
- Hardboard or other compressed paper products
If you suffer from allergies, some woods, especially aromatic cedar, should also be used with caution.
Wood Burning Safety Tips
Use care and common sense when it comes to feeding your wood stove. Although you do need some paper to start your stove, only use enough to get the fire going. Excessive use of starter paper will just add to the creosote buildup.
Safety, of course, is a major concern when operating any wood-burning appliance. Always comply with all recommended clearances and protect flooring with a fire-resistant floor pad. Make sure you have an active carbon monoxide alarm in the area and that your home is equipped with working smoke alarms.