Extension Service Garden Hints

Is your firewood dry enough to burn efficiently?

CORVALLIS – The higher your firewood’s moisture content, the less efficiently it burns. If you don’t let it dry long enough under the right conditions before you burn it, you’ll get a smoky fire without much heat.

The smoke from a low-temperature fire contains gases and acids that condense on your chimney to form creosote – a substance that can ignite and cause a major fire.

Burning green wood also means you have to clean your chimney more often. Plus, you’ll have to work harder to get your fire going, as some of the wood’s moisture must boil and evaporate before it will ignite.

Seasoned firewood contains less than 20 percent moisture and generally takes from six to eight months – and sometimes up to more than a year – to dry, or cure. Much depends on the weather, the type of wood you have and how you prepare and store it. Hardwood such as oak takes longer to dry than softwood like Douglas fir or pine.

The Oregon State University Extension Service offers some hints on how to make sure the firewood you purchase or cut is dry enough to burn efficiently:

• Look for cracking at the ends of split wood. Cracks indicate that the ends are dry, although the center of the wood may still be wet. Knock 2 pieces of firewood with cracked ends together. They’ll make a sharp cracking noise if they’re dry. A dull thud indicates the pieces are wet.
• Borrow or purchase a device that determines the moisture content of firewood by measuring its resistance to an electric current.
• Weigh a small piece of firewood cut from the middle of a large piece. Record the weight in ounces. Dry the small piece overnight at 200 to 300 degrees in your oven. Weigh it again while it is still warm. The difference in weight is the weight of the water in the wood. Divide the weight of the water by the oven-dry weight in the wood to find the moisture content of your firewood. Wood is ready to burn when the moisture content is less than 20 percent.

Split wood right after you cut it. It dries faster split. Don’t forget to cut kindling too, and let it dry.

Stack firewood off the ground to allow air to circulate under the stack and around the pieces. Crossing the wood log-cabin style promotes good air flow within the stack. Do not stack wood directly up against an outbuilding or house.

A simple and effective way to stack and shelter firewood is on a pallet, stacked log-cabin style, with a sheet of clear UV–inhibited polyethylene draped over the top of the stack to allow sunlight through to heat the stack. Leave the sides open to allow air to circulate. Secure the polyethylene with a few pieces of wood or rocks. Once the firewood is dry, replace it with a sturdier nylon or canvas tarp.

By: Carol Savonen
Source: Steve Bowers

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