Wood's Warmth: There is a lot to know about how to use it

Wood was our first fuel source and is renewable as opposed to coal, oil and natural gas. Research shows that there is enough fuel wood available in the nation to heat more than half of the homes each year.

A hundred years ago, wood supplied most of North Carolina's energy. Although some people today still use a fireplace to supplement their heat supply, most just use it for enjoyment.

If you are in the market for firewood, keep in mind that when firewood is first cut, it contains a good bit of water. One fresh-cut cord of oak may have enough water to fill 5.5 55-gallon drums.

How big is a cord of wood?

A cord of wood is 128 cubic feet of cut and split firewood. A rectangular stack is usually 2-foot pieces, stacked 4 feet high and 16 feet long.

What is the best wood for burning?

No species of wood is unsuitable for burning, but most hardwoods are better than softwoods. Such hardwood trees as holly, elm, maple, oak and ash burn longer and produce more heat than most softwood. Softwood trees are usually evergreen, bear cones and have needles or scale-like leaves. They include pines, spruces, firs and cedars.

Pine is actually as good a heat source as hardwoods. It yields slightly more heat per pound because it has more resins than most hardwoods.

What is seasoned wood?

Seasoned wood has been air dried for about six months or more. When wood is first cut, water makes up 40 percent to 50 percent of its weight. Drying allows the wood to burn easily and give up a high proportion of its heat value.

What causes creosote buildup?

When wood is heated, some of its chemical makeup is first changed to a gas; it ignites if the fire is hot enough. If the fire is not hot enough, the gas becomes part of the smoke. If the gas contacts a surface cool enough or evaporating water cools the burning process, the gases will condense back to a liquid or a solid.

Over time, this layer of liquid buildup, called 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.

Unfortunately, burning wood at relatively low temperatures can cause build-up on fireplace or wood heater walls, chimneys and flue pipes. Burning poorly seasoned wood favors creosote build-up too because evaporating water cools the burning process.

Many people think that pine firewood produces more creosote than hardwood, but research has shown that this is not true. 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.

One solution to this is automatic-feed wood-pellet stoves.

How can you tell if firewood is dry enough to burn efficiently?

It is not easy, but there are ways. For one thing, 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. The real indication is weight. Because of the water in it, unseasoned wood is heavier.

Will the insects in firewood eat my furniture?

For the most part, firewood insects and other arthropods are a nuisance and do not cause harm to the home, furnishings or humans. Firewood insects usually belong to one of two groups: those that actively feed on wood and those looking for shelter.

Beetles are the most common wood-infesting insects found in firewood. In the forest, their activities ensure that the resources in the wood are broken down and recycled.

The potential for these insects to infest structural wood in the house is very low. In addition, the moisture content of the wood usually has to be much higher that than found in structural wood in the home. Sometimes the adult emerges after logs are brought indoors.

Carpenter ants and termites may also be found in firewood that has been wet or stacked in one place for a long time. Termite colonies are in the soil, so only workers are found in the wood.

Termites form mud tunnels and this mud can be found in wood that they are attacking. Carpenter-ant galleries are very clean, with no mud or sawdust. Individuals brought into the house in logs will not start an infestation, but a colony may exist in old woodpiles outdoors.

Many insects look over wintering sites under loose bark or in hollow trees. These creatures will become active after warming up indoors. These can be swatted and vacuumed as they appear.

These insects are not able to survive for extended periods indoors. They will not multiply or become established in the home.

What can I do to reduce an insect invasion from firewood?

Avoid stacking the wood directly on the ground, in or against the house for long periods. This will keep the wood from getting too wet and reduce the chances for invasion by termites and carpenter ants.

Use the oldest wood first. Try not to carry over large quantities of firewood from season to season and avoid the tendency to stack new wood on top of old wood.

Cover the wood during the summer and fall. This will keep it drier and exclude some creatures seeking over wintering sites. Shake or knock logs together sharply to dislodge insects and brush off any obvious structures such as webbing or cocoons before bringing it inside.

Bring in small amounts of firewood that can be used up in a day or so and keep it stacked in a cool area (e.g., garage or porch) until it is burned. When wood warms up, the creatures in or on it will become active.

Do not treat firewood with insecticides. It is unnecessary and potentially dangerous because of fumes that may be produced when the insecticides burn.

Wendi Hartup has worked for NC Cooperative Extension in Forsyth County since 2005. She educates citizens on environmental issues, wildlife control and solutions to stormwater runoff. You may find Wendi in a local creek looking for indicator organisms, instructing how to fix erosion with a rain garden, identifying aquatic weeds or advising how to get rid of creepy crawlies. Prior to Extension, Wendi spent 9 years teaching Alabama citizens how to evaluate physical, chemical and biological characteristics of water. Wendi has an M.S. in Fisheries Conservation from Auburn University and a B.S. in Marine Biology from Troy University. To learn more about Wendi and her work contact her at wendi_hartup@ncsu.edu.