Know what you are buying with firewood
Q. I usually use cottonwood in my winter fireplace, but I heard this might not be the best choice. Why, and what should I look out for when choosing the best kind of firewood?
A. Anything that burns will give off a specific amount of BTUs (British thermal units). Some things, of course, burn better than others. For instance, a paid off mortgage note, or mailings from the opposite party of one's political leanings, both burn quite nicely.
However, in these days of ecological awareness, what one puts in a fireplace or wood burning stove requires more consideration. All wood produces the same amount of BTUs per pound. So why use oak, maple or ash, instead of cottonwood?
The answer is in the BTU/pound ratio. Red oak is very dense at 42 pounds per cubic foot. Cottonwood is much lighter at 28 pounds per cubic foot. So, you would need to burn nearly twice as much cottonwood as oak to achieve the same amount of BTUs. Twice as many trips to the woodshed, twice as much stoking the fire, twice as much ash to remove. A full cord (4 feet high, 4 feet wide and 8 feet long) of mixed oak will yield about 25 million BTUs per cord. Cottonwood will yield about 16.
There are some benefits to using cottonwood. It is easy to handle, being light. It starts easily, and is less expensive per piece. These attributes would be beneficial to someone with diminished strength, who is using this wood for occasional decorative, rather than functional, fire.
In selecting any wood for burning, one should seek fully dried wood, as “green” wood will produce not only more smoke, but also creosote. While smoke is more of a nuisance, but can affect your neighbors, creosote is a potential danger as a source of chimney fires. Dried wood will exhibit small checkered patterns in the ends of the logs.
Most firewood in the Chicago area is sold by “face cords.” A face cord is still 4 feet high and 8 feet long, but there is no standard for the width. Consequently, using a reputable firewood source is important. A supplier advertising a face cord for, say, $100, may have nothing but 12-inch and 14-inch pieces, whereas another dealer advertising a $140 face cord may have pieces all 18 inches or longer.
Store the bulk of your firewood away from the house, tarped, and off the ground with a rack or other means to provide air circulation and discourage rodents and insects from coming into your house. Ensure your fireplace or wood stove is inspected and cleaned prior to the start of each heating season. A good mantra for firewood selection is “buy locally, burn locally.” The ban on transporting ash tree wood was lifted in 2015, as the emerald ash borer is prevalent in over half the state.
With careful selection, purchase, and storage of firewood, you will enjoy many cozy evenings in front of a warming, cheery fire.
— Matt Steichmann
• Provided by Master Gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines, and University of Illinois Extension, North Cook Branch Office, Arlington Heights. Call (847) 298-3502 on Wednesdays or email northcookmg@gmail.com. Visit web.extension.illinois.edu/mg.