Firewood is better than money in the bank. It’s the tangible result of your labor, and it represents warmth and security through winter. If you know how to dry firewood properly, wood heat can be a clean, renewable energy that’s more accessible than solar or wind.
The three essential ingredients for efficient and environmentally appropriate wood heating are good stove technology, good fire-building techniques and good fuel. We’ve covered the first two topics in the past (see “Resources” at the end of this article). Now let’s look at what you need to know to have the best firewood.
Knowing how to dry firewood correctly is essential: Every serious wood burner must understand that wood dries slowly. Good firewood should have a moisture content between 15 and 20 percent, and it takes a long time for newly processed wood to dry to that level because the native moisture content of trees ranges from 30 to 50 percent. The efficiency losses resulting from burning wet wood can be as much as 30 percent
Here is a one-sentence prescription for good firewood: Logs should be cut to the correct length, split to the right size range for your heater, and stacked off of the ground in single rows in the open in early spring to be ready for burning in fall.
However, hard species such as oak and hickory usually take longer than a summer to dry. Bigger chunks of firewood dry more slowly, and if you live in a damp climate, your wood will take longer to dry. If you don’t have an open, sunny location to stack your wood, it may take more than the summer to dry. Unless your conditions for drying firewood are optimal, you should prepare your firewood a year ahead.
How to Dry Firewood: The Basics
Firewood that isn’t dry is slow to ignite. It smokes and smolders in the fire, causing both indoor and outdoor air pollution and leaving creosote deposits in the chimney. But that’s not all.
It takes a lot of energy to heat and vaporize the water in wet wood. Up to 15 percent of the energy content of green wood can be consumed turning water into steam and superheating it to the combustion temperature. Wet wood is so reluctant to burn that part of its potential heat energy is wasted as smoke, and it creates a sluggish fire that will smolder and make little heat unless the air control is left wide open. But an open air control will cause much of the heat produced to be rinsed out of the firebox and right up the chimney by such a high airflow rate.
In contrast, properly seasoned wood lights easily, burns cleanly and efficiently, and will continue to flame even if the air control is turned down for an extended burn.
There are several indicators of firewood moisture. Use all of these indicators in judging your firewood’s moisture content, because relying on just one or two could give a false result.
- Dry wood is lighter in weight.
- Dry wood has cracks in its end grain.
- If you bang two pieces of dry wood together, the sound is hollow, whereas wet wood makes a dull thud.
- Firewood darkens from white or cream to gray or yellow as it seasons.
- The exposed face of a freshly split piece of seasoned wood feels warm and dry, but green wood feels cool and damp.
- Green firewood sizzles in a fire.
You could also use a wood moisture meter, although they can be costly and the manual methods will work just as well.
Where to Buy Firewood
You should first consider how much firewood you will need before buying. I burn about four full cords for my annual heating and cooking needs here in Ontario, Canada, but the amount of wood you will need depends entirely on house size and age, climate zone, and whether wood is a primary or supplementary heat and energy source.
Finding cheap firewood is like a hobby among many hard-core woodburners, and people new to wood heating often worry about being overcharged or getting poor-quality wood from a dealer. Although the key to lower cost is to do more of the processing yourself, you don’t need to become a lumberjack to reduce your wood fuel costs. Here are four ways to save on firewood:
1. If you have a suitable vehicle, pick up the wood yourself.
2. Get your wood delivered in log lengths from a logging company so you can cut it to length and split it yourself. You won’t need a truck, but you will need a chain saw and probably a splitter. In addition to sizable cost savings, you’ll get to custom cut and split the wood exactly as you want it.
3. Scavenge wood from various sources, including tree removal companies, mill cutoffs, and neighbors who take down old trees. Sharp-eyed scavengers can get their whole year’s worth of firewood for just the cost of picking it up.
4. The ultimate way to save money is to harvest and process the trees yourself, using trees from your own property or from public lands under a firewood permit you’d purchased from the government. Either way, the cost of the wood is low, but you’ll need some serious equipment (at least a truck or trailer and a chain saw), physical strength and a number of skills that take time to learn. The most difficult challenge is gaining enough experience so you can properly use and maintain a chain saw and fell a tree without getting into trouble. Professional logging is one of the most dangerous occupations in North America, and the risk to amateurs harvesting logs for firewood is even greater because of inexperience. (See “Resources” at the end of this article for more on felling trees.)
How to Know You’re Getting Good Value
The only way to compare firewood prices is if the amount of wood offered for a given price is expressed as a volume, which is termed a “cord.” A full cord of wood is a stack 8 feet long, 4 feet wide and 4 feet high, with a volume of 128 cubic feet (1,728 cubic inches). Dealers usually sell fractions of cords, and they may use the term “face cord,” which should be a stack 8 feet long, 4 feet high and as wide as the individual pieces (normally between 12 and 24 inches). The most common firewood length is 16 inches, and a face cord of 16-inch logs has a volume of about 43 cubic feet — one-third of a full cord.
Provided you know the average piece length in a stack, you can calculate how many cords the stack contains to compare prices among suppliers. To determine how many full cords are in a stack, multiply the length of the logs by the height of the stack, then again by the width of the stack, all in inches. Next, convert the volume to cubic feet by dividing by 1,728. Divide that result by 128 for the number of full cords.
Beware of dealers who offer to sell you a pickup truckload or a random pile of wood, as it will be difficult to calculate the wood’s volume. You should stack the wood and measure it to be sure you have received the volume you paid for if you cannot buy it already in a stack or if you have it delivered.
Qualities of the Best Firewood
The length of firewood pieces should be consistent for efficient stacking and burning. Of course, when you cut up a log and you get to the last piece, it is rarely the right length. If you adjust the length of the last couple of cuts to create full-length pieces, you can end up with some pieces that are too long to fit properly in your heater. Let the last piece be a short one, which you can split for kindling.
Firewood pieces should be at least 2 inches shorter than your firebox so they can be loaded easily without jamming. But the firebox dimension is not the only guide. For example, some woodstoves and heating fireplaces have fireboxes as wide as 2 feet. Handling firewood that is more than about 16 inches in length is difficult, and will make stoking the fire an unpleasant task.
Excellent firewood is split to the proper size range. Using a range of piece sizes makes stoking the fire more convenient and results in less air pollution. Smaller pieces ignite more quickly and, because you will need to light new fires frequently and rekindle from coals a few times a day, these smaller pieces can make your fires respond more quickly and waste less fuel as smoke. An additional benefit of smaller pieces is that they dry more quickly than large chunks of wood.
The old-timers used to split firewood only minimally, leaving it in fairly big blocks because old, leaky cast-iron stoves would burn out of control if fed smaller pieces of dry firewood. Modern wood heaters have smaller fireboxes, and houses are more energy efficient than they were 50 years ago. Today’s advanced combustion heaters do best on a diet of firewood split far smaller than was traditional. For most modern heaters, no piece should have a cross section wider than 6 inches across, and most of the pieces should range from 3 to 6 inches. Wood furnaces and boilers have large fireboxes in which big fires are burned, so they can handle bigger pieces of firewood — but no wood for home heating should have a diameter greater than 8 inches.
The traditional view is that the best firewood is from hardwood tree species. In some regions, the hardest species available are oak or maple. In others, especially in the West and North, birch or fir can be the hardest local woods. A given volume of oak or maple has almost twice the energy content of and produces a longer-lasting fire and hotter bed of charcoal than soft species such as poplar, aspen or willow, so fewer cords would be needed.
But let me offer another take. You will need to run your stove at high output for only two or three months in winter. In spring and fall, you won’t need as much heat or especially long-lasting fires, so you can burn softer wood species during milder weather. Plus, softwood fires don’t overheat the house if you just need to take the chill off in the morning.
Good Firewood Is Clean. If logs were skidded through mud during harvesting, they will make less desirable firewood. Your saw’s chain will need sharpening after every few cuts because the grit in the tree bark will be like sandpaper. Also, your wood storage area will become dusty, and the dust kicked up as you stack the wood will make stacking an unpleasant task and will end up in the wood box in your living space. Look for firewood that was harvested and moved in winter so its bark is free of dirt.
How to Split Firewood
Some people love splitting firewood by hand. Other people, like me, hate it, even though I have spent many hours doing just that. If you decide to split wood, start with the right equipment and setup.
Regular axes are not the best for splitting wood because they are too light and tend to get stuck. Use a splitting maul, which is like a 6- or 8-pound sledgehammer with a blunt blade at one end. When you swing it, you develop a lot of momentum, increasing your chances of a successful split.
You’ll need a big piece of tree trunk about 18 inches in diameter and 12 to 18 inches tall to make a solid splitting block. Getting the log up off the ground will help each strike hit at about the right angle and reduces the chance that a missed swing will hit your feet. (Speaking of feet, you’ll also need some tough boots, preferably a pair with steel toes. Leather gloves are also advisable.)
Here’s an innovation to make splitting firewood much easier: Fasten an old tire to the top of your splitting block by cutting tabs on one side, folding them down and screwing them to the sides of the block (see illustration in the Image Gallery). Place the logs to be split inside the tire, and when you strike them with the maul they will stay put until you have split them into as many pieces as you want. This will greatly reduce the number of times you’ll need to bend over to pick up pieces, which can be the most tiring part of splitting by hand.
If you have a serious amount of wood to split you can up the ante by buying or renting a power splitter (see illustration in the Image Gallery). Splitters come in a range of sizes, capacities and prices, from light-duty, bench-mount electric models, to gas-powered splitters on wheels, to tractor-mounted wood splitter attachments. Prices range from a few hundred to several thousand dollars.
Some homesteaders use electric chain saws and wood splitters powered by off-grid, solar-electric generating systems to produce firewood with a tiny carbon footprint.
However you split your wood, I highly recommend using a kindling maul — similar to a splitting maul but weighs only 2 or 3 pounds and has a 12- to 14-inch handle — to process your wood into kindling. Its extra weight and momentum will out-perform an axe or hatchet, and the tool is much safer because it’s not as sharp.
How to Stack Firewood
Firewood dries fastest if it’s stacked in a single row out in the open where the sun can warm it and breezes can blow away the moisture. This means the wood should be stacked for drying away from the house, then moved to the house and stacked again just before the heating season starts.
It’s a good idea to cover the tops of the piles, although this is not critical until the last month of drying. If the fall weather is rainy, as it can be in many regions, the rain-soaked wood will end up in your wood storage area, which won’t be desirable.
You can stack the green wood in a shed to dry, but it will take at least twice as long to dry. Some people do this and it works fine, but don’t deceive yourself into thinking that wood stacked in a woodshed will dry over the summer months. It won’t, unless you live in a desert. Whichever method you choose, your wood heating adventures should soon stack up to serious savings.
Woodstoves and Fire-Building Techniques
Firewood enthusiast and wood heat expert John Gulland has written extensively on heating with wood and processing wood fuel. Find out more about wood heat and all things firewood at Gulland’s website dedicated to wood heating tips and techniques.