If you're intending to burn wood to heat your home this winter, you'd better make your first priority finding the wood to feed it.

Firewood supplies are already scarce. Many firewood dealers are delivering seasoned wood to long-term customers only. Some, but not all, will deliver green wood, but many dealers have a backlog until fall.

The truth about green wood
The moisture content of green wood averages 60 percent to more than 80 percent by weight, depending on when it was cut.

It takes about six months to air-dry a cord of cut-and-split wood to 30 percent moisture content, and a year or more to reach the 20 percent moisture desirable for the safest, most efficient burn.

If you try to burn green wood, evaporating all that water from your fuel will use as much as 15 percent of its potential heat. Allowing green wood to smolder also promotes a buildup of creosote in the chimney, increasing the risk of a dangerous chimney fire.

Let nature dry your wood
In almost every case, it's more inexpensive to let nature air-dry your wood before you burn it. That means the green wood you buy or cut this fall might not be ready to burn until the 2009-2010 heating season.

How much wood do you need?
The amount of wood required to heat a house depends on a number of factors: the size and interior layout of the house, how weather-tight the house is and the type and efficiency of the wood stove. A 1500-square-foot, fairly weather-tight New Hampshire house will burn between four and five cords of seasoned wood during an average New Hampshire heating season.

High prices
A quick perusal of your local weekly newspaper will show advertised prices exceeding $200 for a cord of green wood and more than $300 for a cord of seasoned wood. Don't delay too long shopping around for better deals on firewood, because prices are bound to increase as winter gets closer and supplies disappear.

Don't commit roadside thievery
By the way, if you've been watching the tree crews trimming the branches off trees close to utility lines and thinking about stopping by later with a pickup truck to collect that wood, think again. Those trees and branches belong to the folks who own the road frontage, and you need permission from them to scavenge the wood.

Where to look for firewood
If you're in the market for firewood, check your local paper, or ask your neighbors and friends about dealers they might know. On-line classifieds, such as Craigslist, are good resources for locating wood as well.

Ask the dealer how long the wood you plan to buy has been drying since it was cut and split. Learn the species mix of the dealer's wood, too. The denser the wood, the longer it will take to dry. Oak, for example, may take more than a year to dry to the desirable 20 percent moisture content.

Know what you're getting
Be sure to clarify what measure of wood you are buying. By state law, a cord of wood is 128 cubic feet of air, bark, and wood. That's a pile of wood 8 feet long by 4 feet high by 4 feet wide.

A vendor may legally sell a fraction of a cord, but must represent it accurately as such (e.g., a half-cord). Remember that stacking a cord is an imperfect skill, so the cord will vary slightly in size every time it is stacked.

Buyer beware
Meet the delivery truck before the load is dumped to make sure you are satisfied by the mixture of species and cleanliness, and tell the driver where you want the wood dumped. Most firewood dealers don't want to return to your house to reload their truck. Ask in advance about any delivery surcharges.

Don't pay for wood in advance of delivery. Ask for a sales invoice that includes the name and address of the firewood selller, the amount and species mix of wood delivered, and the price charged.

Stacking and storing your wood
Unless you've arranged otherwise, it's up to you to restack the pile. Stack it outside in a well-ventilated area off the ground—used pallets make a good platform if you don't have a woodshed. Don't cover your stacked wood until about a month or so before you begin to use it. This will encourage natural air circulation to drive the moisture from the wood.

Even if you're buying your firewood cut, split and delivered, the work of stacking it, loading your stove all winter, and removing the ashes will enable you to understand the old adage "wood warms you twice." At least.

For more information
From cutting your own firewood to managing the ashes from your stove, our new Heating with Wood Web pages offer information on all aspects of heating your home with wood.

By Tim Fleury, UNH Cooperative Extension Forest Resources Educator