Heating With Wood:
This NebGuide explains the basics of producing, harvesting and processing ﬁrewood.
Our forefathers heated their homes with wood because it was the only energy source available. Today, most people heat their home with electricity or natural gas, but wood heat remains a viable home heating alternative.
Heating with wood provides several advantages over other sources of energy. Wood heat does not stop working when there is a blackout. With electric heat, you may ﬁnd yourself in the cold when severe winter weather interrupts electrical service.
Heating with wood is also environmentally friendly. Burning wood produces little pollution, especially with modern high-efﬁciency stoves. Additionally, ashes from your ﬁreplace or wood stove may be used in your garden to prevent pests and enrich the soil.
Wood is a renewable resource, as compared to ﬁnite fossil fuels, such as coal or gas. Fuelwood can be harvested from low-quality trees in woodlands, providing more space for the remaining healthier, higher quality trees.
Each species of wood differs widely in its characteristics (see Table I on page 2). For example, a cord of white oak ﬁrewood produces 29 million BTUs of heat, while one cord of linden ﬁrewood produces 13.8 million BTUs. High-density hardwoods, such as hickory, oak, ash, red elm and walnut, produce the most heat per cord and burn slowly and cleanly. In general, if heating efﬁciency is important, high-density woods, particularly hardwood species, are more desirable. Softwoods, such as most spruces, pines and junipers, and low-density hardwoods, such as cottonwood and willow, burn quickly and produce less heat per cord than dense hardwoods.
Because of resins in softwoods, they tend to smoke and spark and may present safety hazards. Softwoods also produce more creosote, a sticky tarlike substance that clings to chimneys and increases the risk of chimney ﬁres.
The standard measure for ﬁrewood is the “cord.” A cord may be either a full cord or a face cord. A full cord is a stack of wood 4 feet tall, 8 feet wide and 4 feet deep (128 cubic feet). The weight of a cord of wood varies by species (Table I).
A face cord is a stack of wood 4 feet high, 8 feet long and approximately 12 to 18 inches deep. The weight of a face cord also varies by species.
Firewood may also be measured by the “pickup load.” This measure is imprecise, but a full-sized pickup with an 8foot bed will hold approximately one-third to one-half cord of wood, depending on how it is loaded. A pickup bed will hold more when wood is stacked, rather than thrown.
The number of trees per cord depends on the size of the tree (Table II). A tree’s diameter is measured at a height 4 1/2 feet from the ground. This measure is called diameter at breast height (DBH). If trees 5 inches DBH are harvested for ﬁrewood, it will require 46 to 55 trees to make one full cord of ﬁrewood. However, one tree 22 inches DBH will produce one full cord of ﬁrewood.
Table II. Firewood cutter’s rule of thumb.
|Tree Size||Number of Trees|
|(diameter at breast height)||Per Cord|
Depending on the type and quality of wood stove used; the type of wood burned; and the size, insulation and desired temperature of the area to be heated, you may need 4 1/2 to seven full cords of wood per year to heat your home. If you use wood heat as a partial heat source for your home, you may need only 1 1/2 to three full cords of wood per year. If you use a ﬁreplace occasionally, you may only need one-half cord of wood per year.
Table I. Firewood facts for Nebraska trees.
Weight (lbs./cord) Heat/Cord % Green Ease of Overall Species Green Dry (Million BTUs) Ash Splitting Smoke Sparks Coals Fragrance Quality
Apple Ash, Green Basswood (Linden) Birch, Paper Boxelder Buckeye, Ohio Catalpa Cherry, Black Coffeetree, Kentucky Cottonwood Douglas-Fir Elm, American Elm, Red Elm, Siberian Fir, Concolor Hackberry Hickory, Bitternut Hickory, Shagbark Honeylocust Ironwood Juniper, Rocky Mountain Locust, Black Maple, Other Maple, Silver Mulberry Oak, Bur Oak, Red* Oak, White Osage-Orange Pine, Eastern White Pine, Jack Pine, Ponderosa Redcedar, Eastern Spruce Sycamore Walnut, Black Willow 4850 4184 4404 4312 3589 4210 4560 3696 3872 4640 3319 4456 4800 3800 3585 3984 5032 5104 4640 4590 3535 4616 4684 3904 4712 4960 4888 5573 5120 2780 3200 3600 2950 2800 5096 4584 4320 3888 2880 1984 2992 2632 1984 2360 2928 3112 2272 2970 2872 3112 3020 2104 3048 3832 3952 3832 4016 3150 4016 3680 2752 3712 3768 3528 4200 4728 2250 2488 2336 2632 2240 2808 3192 2540
17.6 135 100
82 102 108
79 103 100 108 105
73 106 134 138 133 140 109 140 128
95 129 131 123 146 165
Medium Easy Easy Medium Difﬁcult Medium Difﬁcult Easy Medium Easy Easy Difﬁcult Easy Difﬁcult Easy Easy Medium Difﬁcult Easy Difﬁcult Medium Difﬁcult Easy Medium Easy Easy Medium Medium Easy Medium Difﬁcult Easy Medium Easy Difﬁcult Easy Easy Low Low Medium Medium Medium Low Medium Low Low Medium High Medium Medium Medium Medium Low Low Low Low Medium Medium Low Low Low Medium Low Low Low Low Medium Low Medium Medium Medium Medium Low Low Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Few Many Few Few Few Many Few Few Few Many Few Many Many Many Many Few Few Few Good Good Poor Good Poor Poor Good Excellent Good Good Fair Excellent Excellent Good Poor Good Excellent Excellent Excellent Excellent Poor Excellent Excellent Excellent Excellent Excellent Excellent Excellent Excellent Poor Poor Fair Poor Poor Good Good Good Excellent Slight Good Slight Slight Slight Bad Excellent Good Slight Slight Good Good Fair Slight Slight Excellent Excellent Slight Slight Excellent Slight Good Good Good Good Good Good Excellent Good Good Good Excellent Slight Slight Good Slight Excellent Excellent Fair Fair Fair Fair Fair Good Good Fair Good Fair Good Fair Fair Good Excellent Excellent Excellent Excellent Fair Excellent Excellent Fair Excellent Excellent Excellent Excellent Excellent Fair Fair Fair Fair Fair Good Excellent Poor
*Pin Oak is in the same group as Red Oak.
As prices of other traditional heating fuels vary, the savings based on using wood heat also vary (Table III).
Conventional energy source Wood
1 gallon #2 fuel oil 22.2 pounds 1 therm (100 cubic feet) natural gas 14 pounds 1 gallon propane 14.6 pounds 1 kilowatt/hour electricity 0.59 pounds 1 pound coal 1.56 pounds
Most Nebraska woodlands fall into one of two categories: eastern hardwood and western coniferous. The species most commonly found in Nebraska’s hardwood forests include bur oak, red oak, silver maple, green ash, cottonwood, black willow, hackberry, black walnut, American basswood, boxelder, American elm, honeylocust, hickory and mulberry. While eastern redcedar is a conifer, it is also frequently found in Nebraska hardwood forests. Nebraska’s conifer forests consist primarily of ponderosa pine and Rocky Mountain juniper.
The species composition of a woodland will determine its growth rate. An oak-hickory forest can grow an average of 27 cubic feet per acre annually; a cottonwood forest can grow up to 24 cubic feet per acre annually; and eastern redcedar and maple-basswood forests can each grow up to 22 cubic feet per acre annually. These rates are averages and will vary depending on many factors, such as weather, soil and the woodland’s condition.
The rate of a woodland’s growth can be increased through proper management. By determining the primary objectives for your woodland, taking an inventory of tree species in the area and identifying appropriate management practices, your woodland can become a highly productive, sustainable resource. For more information on woodland management, see NebGuide G97-1329, How to Manage Your Woodlands for Sustained and Maximum Beneﬁts (http://ianrpubs.unl. edu/forestry/g1329.htm).
Harvesting timber from woodlands is the most obvious means of gathering ﬁrewood, but there are other readily available sources as well. Wood waste, such as the logs, limbs and tree tops toppled by storms, can be reclaimed from urban landﬁlls and used as ﬁrewood. As much as 30 percent of the debris in some landﬁlls is wood debris. Other sources of ﬁrewood include industrial wood waste from lumber processors or trees and tree limbs removed during powerline maintenance efforts. Even though the wood from these sources could be free, be sure to seek permission before removing it for personal use.
For those who own a woodlot, cutting trees for fuelwood can improve the quality and growth rate of the remaining trees (Figure 1). To maximize the value of trees in your woodlot, ﬁrst identify high-quality trees of the better timber species.
low fork crooked limbs crowded poor species
Figure 1. Thinning can greatly improve the quality of remaining trees in a woodland. (Image: Woodland Stewardship: A Practical Guide for Midwestern Landowners (1993) by M. Baughman, et al. Minnesota Extension Service, St. Paul, Minn.)
Then, create space around these trees by removing poor quality trees that are crooked, diseased, decayed or of low commercial value. These diseased, dead or damaged trees can be used as ﬁrewood unless they are valuable to wildlife.
Sometimes, straight, reasonably high-quality trees must be removed because they are crowding other good trees. In young woodlots, future timber trees will respond rapidly to increased growing space. Over time, the periodic thinning of the stand will enhance the quality of the remaining timber trees. The trees removed during thinning are a good source of ﬁrewood.
Undesirable timber species, such as boxelder, elm, mulberry and honeylocust, should be harvested for ﬁrewood to encourage the growth of higher-value species, such as black walnut, ash, oak and hackberry.
For safety, you should have a hard hat, ear protection, safety shoes, safety glasses and chain saw chaps (to prevent leg injuries). Never work alone in the woods. It is also a good idea to have a ﬁrst-aid kit and cellular phone with you when cutting timber.
Cutting standing trees requires skill and the proper equipment. You will need a chain saw, extra sharpening chains, chain sharpening and saw maintenance tools, gas and oil and possibly wedges, mauls and an axe.
Remember, one cord of freshly cut wood can weigh more than two tons, so you will also need heavy-duty hauling equipment and a strong back. Keep the axes and saws sharp and well maintained for easy, safe cutting. Sharp tools will also reduce user fatigue. Never let the chain oiler go dry, and keep the chain saw air ﬁlter clean. Refer to your chain saw owner’s manual for proper maintenance guidelines.
There are a number of safety concerns involved with cutting trees. You need to consider factors such as wind direction, the natural lean and balance of the tree, location of large limbs and whether the trunk is hollow or partially rotted. When harvesting ﬁrewood, be careful not to scar or damage the timber trees that are left standing.
Before cutting, clear brush around the tree that could interfere with your work. Pick an escape route for when the tree begins to fall. Plan to move far enough away so the butt end of the tree will not hit you if it kicks back off the stump.
Figures 2 and 3. Illustrations of an undercut and backcut. (Images: Felling and Bucking Hardwoods (1978) by F.J. Petro. Canadian Forestry Service, Ottawa, Ontario.)
Direction of fall
Figure 4. Be aware of your safety zone when felling trees. (Image: Woodland Stewardship: A Practical Guide for Midwestern Landowners
(1993) by M. Baughman, et al. Minnesota Extension Service, St. Paul, Minn.)
A. Make a horizontal cut about one-third of the way through the tree. This cut should be as low as possible and on the side toward the direction you want the tree to fall. This is the undercut (Figure 2).
B. Make a 45-degree downward cut into the horizontal cut to saw out a notch. The wedge of wood forming the notch can then be knocked out (Figure 2).
C. Make a horizontal backcut 1 to 2 inches higher than the ﬁrst cut and on the opposite side of the tree from the ﬁrst cut. Saw toward the notch you just cut in step
B. This is the backcut. Leave 1 to 2 inches of uncut wood as a hinge to hold the tree as it falls. This hinge controls the falling tree (Figure 3).
D. If necessary, use a wedge in the backcut to start the tree falling.
E. Move away at a 45-degree angle from the direction of the falling tree to the side and rear of the tree as it falls (Figure 4).
If a tree becomes lodged in another tree while felling, the safest way to get the tree down is to pull it away from the other tree with a tractor or winch. Never attempt to cut the tree in which the felled tree is lodged, and do not climb either tree.
Once the tree is on the ground, you can begin removing its branches. This process is called “limbing.” While limbing the tree, keep the tree trunk between you and the saw whenever possible. Begin limbing at the base of the trunk and remove limbs from the top of the tree before removing limbs resting on the ground. The likelihood of the tree rolling increases as more branches are removed. Branches resting on the ground help stabilize the tree and should be cut last. Be alert for any movement in the tree or the branches as they are cut and be ready to move away quickly if necessary.
With all the limbs removed from the tree, you’ll need to cut the trunk and large branches into short, ﬁrewood-sized sections. Cut the wood about 4 inches shorter than the length of your ﬁrebox. Watch for metal in the wood, such as fence wire or nails, that will dull the chain saw. Cut logs on the pinching side ﬁrst, then make the ﬁnal cut on the opposite side. Avoid cutting into the ground, as this will quickly dull the saw.
Wood dries more rapidly when a large amount of surface area without bark is exposed to the air. This is why it is important to split ﬁrewood. Split ﬁrewood also ignites easier and is lighter and easier to handle.
The least expensive, but hardest and slowest, way to split wood includes the use of axes, mauls and wedges. Stand pieces of wood upright on a solid block approximately 20 inches high and wider than the piece of wood to be split. Do not split wood directly on the ground, as you could hit your foot or leg. Split toward the center of the wood. You may need to use several wedges to complete the split (Figure 5).
Power log splitters can take much of the labor out of splitting, but the purchase cost of these wood splitters should be weighed against the amount of ﬁrewood to be split. Examples of power log splitters include hydraulic, mechanical jack and screw models, which can be operated from a tractor, automobile or independent power source. Power splitters also can be rented, reducing overall costs.
Log may split
First cut First cut
No splitting occurs Second cut
Figure 5. The correct method for bucking a log. (Image: Woodland Stewardship: A Practical Guide for Midwestern Landowners
(1993) by M. Baughman, et al. Minnesota Extension Service, St. Paul, Minn.)
The primary reason for seasoning ﬁrewood is to get the moisture content of freshly cut logs below 20 percent. Reducing moisture in ﬁrewood increases burning efﬁciency because drier ﬁrewood uses less heat to change water to steam. This means less wood must be harvested, saving you time and money. Also, reducing the amount of moisture in wood decreases the occurrence of ﬁrewood ignition problems, creosote buildup in the chimney, wood decay and insect pests.
Proper splitting and storage are important to the seasoning process. Start harvesting and seasoning your ﬁrewood early; the fall is not the best time to build a ﬁrewood supply for the forthcoming winter. It is best to cut your ﬁrewood one year before you will need it. Some ﬁrewood cutters fell trees in the summer and leave them in place with the branches and leaves intact for two to four weeks. The branches and leaves draw moisture from the wood, accelerating drying.
Air drying ﬁrewood takes time and space. Freshly cut trees are higher in moisture and need six to 12 months to air dry before they will burn efﬁciently. Proper allocation of space for stacking and seasoning ﬁrewood will save you time and problems. Firewood stacks can be messy and present a ﬁre hazard, so avoid stacking them too close to the house. Stacking ﬁrewood too close to the house will also cut down on circulation within the stack and could create insect problems inside the house.
Place ﬁrewood in an open area for rapid drying and to prevent deterioration of the ﬁrewood. Stacked ﬁrewood should be raised off the ground slightly to increase air circulation. Stacking wood under a well-ventilated shelter will reduce drying time by keeping outside moisture off the stack. Shelters made of clear plastic sheeting (4 millimeters thick) located in sunny places can be used to speed up the seasoning process by increasing the temperature within the shelter. However, shelters made of plastic sheeting need to have proper ventilation so moisture can escape.
Harvesting, hauling and preparing ﬁrewood generally take four to 10 hours of work per standard cord. Proper planning and organizing will save you time and headaches during the burning season. Technical assistance is available through your local forester.
Baughman, M., Alm, A., Reed, A., Eiber, T., and Blinn, C. (1993). Woodland Stewardship: A Practical Guide for Midwestern Landowners. Minnesota Extension Service: St. Paul, MN.
NebGuide G79-443, Firewood Plantations. NebGuide G88-881, Heating with Wood: I. Species Characteristics and Volumes. http://ianrpubs.unl.edu/forestry/g881.htm. NebGuide G90-968, Nebraska’s Forest Resources: Acreages and Ownership. http://ianrpubs.unl.edu/forestry/g968.htm. NebGuide G97-1329, How to Manage Your Woodlands for Sustained and Maximum Beneﬁts. http://ianrpubs.unl.edu/forestry/g1329.htm. Petro, F. (1975). Felling and Bucking Hardwoods: How to Improve Your Proﬁt. Canadian Forestry Service: Ottawa, Ontario.
USDA Forest Service Research Paper NC-332, The Forest Resources of Nebraska. (1998). http://188.8.131.52/pubs/viewpub. jsp?index=10017.
University of Missouri Extension Publication G5450, Wood Fuel for Heating. (1995). http://muextension.missouri.edu/explore/ag-guides/forestry/g05450.htm.
Issued March 2005
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