Get Your Firewood This Summer
Summer's a smarter time than fall to obtain your firewood. Why?
by Neil Soderstrom

For efficient burning, firewood needs six months to a year to dry, in a process called seasoning. So, if you wait until fall to cut your own wood, you're too late. And if you wait until fall to have wood delivered, it may not be seasoned well enough, if at all, in spite of the dealer's assurance. Plus, summer prices can be lower, before peak fall demand.

People new to woodheating often learn hard lessons after buying their first firewood. First, the term "seasoned" is a relative thing--suggesting a wood's dryness compared to its high moisture content when first cut. Second, a cord of wood, the advertised selling volume, can be defined in various ways. Finally, it's helpful know the different burning qualities of different wood species.

Classified ads offer to deliver "firewood," and sometimes "seasoned firewood," for prices from $90 to $140 per cord. Looking for value, you may well be tempted to shop by phone for the lowest price. You decide to start with one cord because you don't know how much you'll burn. Fine, they say. They'll deliver that night.

A guy drives up in a pickup heaped with firewood. You watch him toss the wood into a heap in the shadows and hand him $90, pleased with your bargain. But as the pickup heads out, you notice two huge truck tires in its bed--tires that take up considerable volume.

The next morning, you stack your 16- to 20-inch logs in a row that measures not quite 4 x 8 feet, dimensions you'd read somewhere made up a cord of firewood. Your woodburning neighbor stops by to look at your wood, shakes his head, and explains that a full cord should measure 4x8 by 4 feet, not by 16 inches. That guy in the pickup sold you only a third of a cord.

You phone to complain and are told that the dealer delivers face cords, sometimes called fireplace cords, a legitimate selling unit that measures 4x8 by the length of the cut wood. Thus, in order to get a full cord from that dealer's $90 price, you'd have to pay $270. And darned if the fire from that wood doesn't just steam and smolder sullenly, as it labors to boil off its own bound water.

A full cord will fill to overflowing the bed of a small dump truck. When dumped, its heap will measure about 4 feet tall and 12 feet in diameter--a large pile of wood.

Also, the dealer should have split all logs that were of more than 4-inch diameter. Even so, you'll probably find many large, heavy pieces split only once from large trunks. They'll be too heavy to handle with one hand, even by a strong person. If you'll be feeding a woodstove, some of those bigger pieces will need further splitting just to fit inside, let alone to be manageable by all who tend the stove. Further splitting has another advantage--it exposes additional wood surface for air drying, which over time further reduces the moisture content.

Moisture Content

The lower a wood's moisture content, the better it will burn, giving off more heat. Seasoned wood not only burns hotter, it also burns more efficiently, sending fewer unburned volatiles up the chimney flue to condense there as creosote, a tarry substance that creates a significant fire hazard if it ignites. Imagine your chimney top resembling and roaring like an inverted rocket, about to breach the chimney's mortar joints and ignite the adjoining house wall. A scary experience. Call the fire department.

The fire of seasoned wood wastes little energy boiling off water, which can represent 40 to 70 percent of an unseasoned log's weight. The goal of seasoning is to bring the wood's moisture into equilibrium with ambient air, under 10% water by weight. Summer months promote faster drying because warm air has greater capacities to absorb moisture.

Wood Species

Seasoned, dry wood produces heat in relation to its weight--not its volume. Pound for pound, wood species of differing density but equal dryness produce the same amount of heat. Thus, because less dense wood has less material available for combustion, you may need two cords of a lightweight wood to produce the same amount of heat as a heavier, denser wood. (A full cord of good, well-seasoned wood, burned in an efficient wood stove, will yield roughly the equivalent of 190 gallons of fuel oil or 25,000 cubic feet of natural gas.)

Foresters and firewood dealers refer to woods either as hardwoods or softwoods. Hardwoods come from deciduous trees--broad-leaved trees that shed their leaves in fall. Softwoods come from coniferous trees--cone-bearing evergreens with needle-like leaves.

Although there are exceptions, hardwoods are so named because most are denser and thus harder than softwoods. Because most softwoods (conifers) are lightweight and have a high resin content that produces more creosote in the chimney, they are not recommended for burning.

When cutting your own wood or shopping by phone, it's helpful to know relative heating values of local wood species. By phone, inquire what woods will predominate in the delivery. That question alone might give pause to a dealer who might otherwise have tried to dump low-heat woods on you.

   · High-Heat Firewoods: In our region, the best and densest firewoods include oaks, hickories, locusts, sweet and yellow birches, beech, walnut, sugar maple, nearly all fruit woods, hawthorns, and hornbeam. You'll know when you've picked up a hornbeam log by its smoothly wavy, gray bark and heft that suggests a lead pipe.

   · Medium-Weight Firewoods: These also serve well when mixed with denser woods and include ash, red maple, paper birch, sweet gum, elm, and sycamore. Ash is unique in its low moisture content when green, which allows you to burn it soon after splitting. And ash splits easily.

   · Low-Heat Firewoods: These include willows, basswood, cottonwood, and yellow (tulip) poplar. Seasoned, they weigh only about half as much as high-heat firewoods, even though their high moisture content when green may suggest they are denser than they are. They're not good for heating because they burn up quickly, but can serve well as kindling, also because they split easily.

Choosing a Firewood Dealer

Your best advisor could be an experienced woodburning neighbor, well satisfied with a local dealer. Lacking that neighbor, you'd be prudent to visit the dealer's woodpile and examine the wood, especially if you've waited until fall to order. Some dealers cut and split a mountain of wood months before delivery. Others may be cutting and splitting barely ahead of demand.

Seasoned wood ends look dry and show many shrinkage cracks. Whacked together, seasoned pieces resound like bowling pins. Moisture-laden, green woods, on the other hand, emit a dull thud. Also inquire how the dealer determines cord volume.

If you have a wood stove be sure to specify maximum length your stove will accept--18 inches or less for smaller stoves. That's important because many dealers cut for average lengths of 20 inches. Also emphasize that you don't want many 6- to 10-inch stubs, because they don't stack well and don't burn as efficiently as longer pieces.

Seasoning Wood

First, you want to promote evaporation of what's known as free and bound moisture. Second, you want to prevent the wood's picking up moisture from rain and snow--which requires shelter, the airier the better.

In summer, it doesn't hurt to leave firewood exposed to rain as long as direct sun dries it. But in shade, exposed firewood tends to remain damp, which promotes rot, reducing wood density and heating value.

Because tree bark tends to retard evaporation, be sure to split any unsplit logs of more than 4-inch diameter. The resinous, watertight bark of birch species especially retains moisture, which means that larger birch logs can rot quickly unless split into quarters.

To promote air circulation and thus fastest seasoning, stack the wood loosely, even "chimney fashion," two logs side by side, then two more perpendicular on top of them, and so on. Also, elevate the bottom logs on thin masonry blocks or scrap lumber, both to prevent wicking of ground moisture and to promote circulation.

Safety Notes

   · Insect Precaution: Because carpenter ants like damp wood for their nests, avoid placing a woodpile near your house.

   · Woodburner Installation: Before burning wood in any new wood stove or fireplace, have local officials inspect the installation for clearances. A wood stove placed too near a wooden wall or mantel can heat it enough to ignite it.

   · Chimney Cleaning: Be sure your chimney flue is cleaned properly after each woodburning season. With the right equipment, you can clean your own chimney. Most people instead hire chimney cleaners, who for $50-$75 will brush and vacuum the flue and issue you a cleaning certificate. Better cleaners will also climb up on your roof and closely inspect the top of your chimney for signs of deterioration, such as eroded mortar joints that can allow water to enter and begin major damage in freezing temperatures. To correct mortar problems, you need either a mason or an illustrated book on repointing a chimney.

   · Splitting Wood Further: No matter how conscientious your wood dealer, you'll undoubtedly receive some logs that need further splitting, whether to promote seasoning or to create kindling. For denser woods of 16-inches and longer, I recommend a splitting maul with a 6- to 12-pound head, rather than an ax with a 3- to 5-pound head. An ax works pretty well on short lengths of wood. But longer stove lengths with knots and wavy grain tend to resist splitting. In this case, a maul falling almost of its own momentum creates a powerful splitting force. To create the same amount force with an ax, you need to swing hard and fast, making your feet and legs more vulnerable to glancing blows. Because a maul can fall more slowly, a glancing maul head also gives you a split-second more time to jerk your foot out of the way.

Neil Soderstrom is a gardening writer and photographer based in Wingdale, NY, also found at www.agpix.com/soderstrom.