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Purchasing Firewood
Firewood can be purchased in several forms. Although there are a variety of measuring units, firewood is normally sold by the cord, or a fraction of a cord. The dimensions of a "standard cord" is a stack of wood piled 8 feet long, 4 feet wide and 4 feet high. One will not get a full 128 cubic feet of firewood with a standard cord because of the airspace between the pieces of the wood; the amount of wood in such a stack will depend upon the size and straightness of the pieces, how they are split and how the wood is stacked. Because of this, the total cubic feet in a cord can vary from 70 to 90 or more cubic feet.The more services a wood dealer furnishes (such as splitting, delivering and stacking) the more costly purchasing will be. The cost of firewood varies with different geographical areas. Orders for the purchase and delivery of firewood should be placed well in advance of the heating season. Wood purchased during the peak periods is in more demand and becomes more expensive. You will also want to purchase early to guarantee seasoning.
Seasoned wood has a higher heating value than green wood. In general, a cord of green wood will weigh 70 to 100 percent more than seasoned wood. Seasoning takes place until the moisture content in the wood reaches equilibrium with the moisture in the surrounding air. Wood stacked outdoors with good air circulation in a dry, sunny and open are for about six months will be dry enough to support efficient combustion.
The time of year and the size of the wood all have a significant influence on its drying rate. Complete drying is facilitated by the proper storing and stacking of the firewood.
The easiest and best fire, for either a stove or fireplace, is achieved by using a mixture of both softwoods (pines, firs, etc.) and hardwoods, (oak, eucalyptus, etc.) The softwoods facilitate starting the fire, and the hardwoods provide for long burning and good "coaling" qualities. A bed of ashes underneath the grate produces steady heat and aids in igniting new fuel as it is added. The fire will continue burning if small amounts of wood are added at regular intervals. In fact, more efficient combustion results from burning small loads of wood with sufficient air than from burning large loads with minimal air.
Firewood is best stored outside, under cover and close to the house for easy access. It should be stacked on a supporting base (such as cement blocks, pallets or wooden planks) to prevent drawing moisture from the ground, to allow air to circulate, to reduce insect infestation and to reduce dirt accumulation. End braces or stakes can be used to keep the wood pile from collapsing; they can be built to measure accurately a standard cord.
Below is the average energy content of various species of wood.
| Species | Btu/Cord* | Cord Weight (pounds) ** DRY |
Cord Weight (pounds) ** GREEN |
|---|---|---|---|
| Alder, Red | 18.4 - 19.5 | 2000 - 2600 | 3200 - 4100 |
| Ash | 24.5 - 26.0 | 2680 - 3450 | 4630 - 5460 |
| Aspen | 17.0 - 18.0 | 1860 - 2400 | 3020 - 3880 |
| Beech | 28.6 - 30.4 | 3100 - 4000 | 4890 - 6290 |
| Birch | 25.9 - 27.5 | 2840 - 3650 | 4630 - 5960 |
| Cedar, Incense | 17.8 - 20.1 | 1800 - 2350 | 3020 - 3880 |
| Cedar, Port Orford | 20.7 - 23.4 | 2100 - 2700 | 3400 - 4370 |
| Cherry | 22.3 - 23.7 | 2450 - 3150 | 4100 - 5275 |
| Chinquapin | 23.2 - 24.7 | 2580 - 3450 | 3670 - 4720 |
| Cottonwood | 15.8 - 16.8 | 1730 - 2225 | 2700 - 3475 |
| Dogwood | 28.6 - 30.4 | 3130 - 4025 | 5070 - 6520 |
| Douglas-Fir | 23.5 - 26.5 | 2400 - 3075 | 3930 - 5050 |
| Elm | 22.3 - 23.7 | 2450 - 3150 | 4070 - 5170 |
| Eucalyptus | 32.5 - 34.5 | 3550 - 4560 | 6470 - 7320 |
| Fir, Grand | 17.8 - 20.1 | 1800 - 2330 | 3020 - 3880 |
| Fir, Red | 18.3 - 20.6 | 1860 - 2400 | 3140 - 4040 |
| Fir, White | 18.8 - 21.1 | 1900 - 2450 | 3190 - 4100 |
| Hemlock, Western | 21.6 - 24.4 | 2200 - 2830 | 4460 - 5730 |
| Juniper, Western | 23.4 - 26.4 | 2400 - 3050 | 4225 - 5410 |
| Laurel, California | 24.6 - 26.1 | 2690 - 3450 | 4460 - 5730 |
| Locust, Black | 29.5 - 31.4 | 3230 - 4150 | 6030 - 7750 |
| Madrone | 29.1 - 30.9 | 3180 - 4086 | 5070 - 6520 |
| Magnolia | 22.3 - 23.7 | 2440 - 3140 | 4020 - 5170 |
| Maple, Big Leaf | 21.4 - 22.7 | 2350 - 3000 | 3840 - 4940 |
| Oak, Black | 25.8 - 27.4 | 2821 - 3625 | 4450 - 5725 |
| Oak, Live | 34.4 - 36.6 | 3766 - 4840 | 6120 - 7870 |
| Oak, White | 26.4 - 28.0 | 2880 - 3710 | 4890 - 6290 |
| Pine, Jeffery | 19.3 - 21.7 | 1960 - 2520 | 3320 - 4270 |
| Pine, Lodgepole | 19.7 - 22.3 | 2000 - 2580 | 3320 - 4270 |
| Pine, Ponderosa | 19.3 - 21.7 | 1960 - 2520 | 3370 - 4270 |
| Pine, Sugar | 17.3 - 19.6 | 1960 - 2270 | 2970 - 3820 |
| Redwood, Coast | 17.8 - 20.1 | 1810 - 2330 | 3140 - 4040 |
| Spruce, Sitka | 19.3 - 21.7 | 1960 - 2520 | 3190 - 4100 |
| Sweetgum (Liquidambar) | 20.6 - 21.9 | 2255 - 2900 | 4545 - 5840 |
| Sycamore | 21.9 - 23.3 | 2390 - 3080 | 4020 - 5170 |
| Tanoak | 25.9 - 27.5 | 2845 - 3650 | 4770 - 6070 |
| Walnut, Black | 24.5 - 26.0 | 2680 - 3450 | 4450 - 5725 |
| Western Red Cedar | 15.4 - 17.4 | 1570 - 2000 | 2700 - 3475 |
| Willow, Black | 17.5 - 18.6 | 1910 - 2450 | 3140 - 4040 |
* British thermal unit (Btu) values based on specific gravity of 80 cubic feet per cord. 8000 to 8500 Btu per pound for non resinous woods. 8600 to 9700 Btu per pound for resinous woods. ** Weights:
Higher value of range assumes 90 cubic feet of wood per cord. Dry weight at 12 percent moisture content. Green weight at 40 to 60 percent moisture content.
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