Firewood Tips from the Gilmer County UGA Extension Agent


By: Eddie Ayers, County Extension Agent

To me there is nothing more calming than sitting in front of a fire on a cold winter’s night. Gas is efficient
and convenient, but it’s hard to replace the feeling of a wood fire. If you have fire burning devices, here
are a few tips to keep in mind when you are buying and burning wood this winter.

When firewood is first cut, it contains a good bit of water. One fresh-cut cord of oak may have enough
water to fill five and a half 55-gallon drums. In a wood-burning stove or fireplace, that wood has to dry
out before it will burn and boiling off all that water steals a lot of heat away from the house. Firewood
should be “seasoned” before it is burned in the house. In general, the term means the wood has dried to a level that will allow it to burn easily and give up a high proportion of its heat value. Well-seasoned
firewood will have dried to a point that less than 20 percent of its weight is water. So keep in mind that
when the wood is first cut, water makes up 40 percent to 50 percent of its weight.

How can you tell if firewood is dry enough to burn well? It’s not easy, but there are ways. One is to split
a fireplace log and look at the split surfaces. Recently cut wood will have a darker center with lighter,
drier-looking wood near edges or ends, and wet wood will be easier to split than dry wood. When
firewood is very fresh, the bark will be tightly attached. Bark on very dry logs can usually be pulled off
easily. You can also hit two pieces of wood together and if the sound is dull, then it’s full of water and
not dry enough to burn. When dry wood is hit together, it will give off a louder sound.

The real indication is weight. Because of the water in it, unseasoned wood is heavier. Use a bathroom
scale to compare a fixed volume (such as a cardboard boxful) of dry firewood with wood of unknown
moisture content. That will tell something about the degree of seasoning. At the same moisture content,
pound for pound, all wood produces about the same amount of heat. The difference is that some woods
are heavier than others. Oak and hickory logs weigh more than the same size sweet gum or pine logs.
That means you have to carry in and burn more pine or sweet gum logs to get the same amount of heat.
And because it has more natural resins, pine actually yields slightly more heat per pound than hardwoods.

The sticky, gum-like resins in pine firewood have given some people the impression that it produces more
residue buildup, called creosote, than hardwood but research has found this is not true. The buildup on
fireplace or wood heater walls, chimneys, and flue pipes seems more a result of burning wood at relatively
low temperatures. When wood is heated, some of its chemical makeup is first changed to a gas and later
ignited if the fire is hot enough but if the fire’s not hot enough, they become part of the smoke and if they
contact a surface cool enough, they’ll condense back to a liquid or a solid there. Over time, this layer of
creosote becomes thick enough that a hot fire will ignite it in place, causing a chimney fire. Filling a
wood stove at night and closing the damper to reduce airflow can keep a fire burning all night with no
more wood but it’s also likely to form creosote. Burning poorly seasoned wood also favors creosote
buildup because evaporating water cools the burning process. Burning small amounts of wood at high
temperatures is one solution to the problem, but doing that by hand makes for busy and sleepless nights.

If you are buying wood, make sure you and the seller are talking the same language. A cord is an official
measurement and its 4 feet wide, by 4 feet high, and 8 feet long. Wood is often sold as a face cord but it
is not an official measurement. A face cord is 1/3 of a cord because the pile is 16 inches wide instead of 4
feet wide. If you are buying it by the pickup load, keep in mind that a small truck has about ¼ of a cord, a
half ton truck about ½ of a cord, and a long bed with racks might contain close to a cord.

So as the nights get cooler enjoy your fire burning devices, but use them appropriately with the proper
wood. Also, if you did not change your smoke detector battery when the time changed, now is a good
time to do it. Safety in the home is very important. For more information, contact me in the Gilmer
County UGA Extension office.

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