Woodstoves consume on the average slightly less than 4 cords of firewood per year. Less frequently used fireplaces consume about a cord and a half each. Since cutting, hauling, splitting, and stacking that much wood takes a lot of time, effort, and money, most wood burners (particularly those with efficient woodstoves) are interested in the maximum amount of heat for minimum risk and expense.

Fresh-cut "green" wood may weigh two to three tons per cord. The heat value of green wood is reduced by its moisture content, and the amount of moisture in the wood varies by species. Ash typically contains about half as much water as wood; hickory, two-thirds; oak, about three-fourths; white pines have nearly equal amounts of wood and water; and yellow-poplar and other so-called "soft hardwoods" actually contain more water than wood!

Burned green wood cannot produce its potential useful heat, because some of the heat of combustion must be used to eliminate the water. Aging (seasoning or air-drying) firewood allows this moisture to gradually escape before burning, using energy from the sun rather than from the fire to eliminate the water.

It takes as long as a year for split and stacked firewood to reach a stable "air dry" condition. Even then, wood still retains about one-fifth its weight in water, although the heat value is considered to have reached its practical maximum.

The heat value of air-dry wood is mostly dependent on its weight. Hickories and oaks top the list of species, weighing nearly 2 tons per cord air-dry; ash, more than 1 1/2 tons; and yellow-poplar, barely 1 ton per cord.

Now it's already too late to split, stack and dry firewood a year before burning next winter, but don't despair. Six months' storage results in about 90 percent of the air-dry heat value. Furthermore, by stacking off the ground, in an open area, and covering the wood pile to keep off rain, the drying process can be accelerated.

Firewood is generally marketed by the cord (a stack 4 feet by 4 feet by 8 feet) and usually hauled by the "pick-up" load (one-fourth to one-half cord). However, since the wood's heat value depends on weight, buyers should prefer the heavier species such as oak, hickory, and ash. Other characteristics which might be considered important for firewood besides cost include aroma, smoke, ease of ignition, tendency to spark or pop, burning time or intensity, and ease of splitting.

About two-thirds of the state's wood burners cut their own wood supply. These individuals should consider the following information.

Chainsaw safety should be top priority. A chainsaw is the most dangerous piece of equipment most people ever handle. Chainsaws are involved in some 30,000 accidents each year and injuries are usually severe. All available safety equipment should be used, the saw properly maintained and sharpened, and safe operating procedures strictly followed. All reputable dealers should gladly discuss safe and proper chainsaw use.

A cord of efficiently burned firewood can have a heating value of about $150. While this is not to be sneezed at, it certainly won't offset many medical expenses. Gas, transportation and labor costs for cutting, loading, hauling, splitting, and stacking a cord of firewood can exceed $75, which doesn't leave a lot of room for the cost of the wood itself.

The value of trees cut for firewood should be especially important to people cutting on their own woodlots. Low-value trees should be used for firewood. These include small, crooked, partially rotten, low vigor, diseased, dying, and dead trees. Most woodlots have plenty of low-quality trees.

It doesn't take much firewood to figure out that a cord requires many more small trees than large ones. While it takes 2 dozen 6-inch diameter trees per cord, only 1 dozen 8-inch trees or three 13- inch trees, or just 2 of 16-inch diameter would provide the same amount of wood. However, firewood cutters should be aware that those two largest trees could have a value for furniture or veneer as high as $50 to $75 each. Burning them would be almost as senseless as burning the furniture they could have made.

Cutting firewood can actually improve forests. Removal of low-quality trees allows the remaining "crop" trees to grow faster. Many wooded acres can produce one-quarter cord of firewood each year on a continuing basis, while simultaneously producing a valuable timber crop. In some poorer quality forests, all trees should be cut for firewood, to help in establishing a new, better quality stand. The typical woodlot can produce firewood as well as wildlife, timber, and other products. For more forest management advise, woodlot owners may contact the N.C. Forest Service County Ranger or the Cooperative Extension Service.

Revised 2/16/2006.