How do you measure a pile of wood?
In Vermont, firewood is not sold by the bag or the box. It has a unit of measure of its own — written into state law — and rules about how far it is allowed to travel.
The unit is called a cord, and it is a shape. Vermont’s Department of Forests, Parks and Recreation puts it plainly: “A ‘cord’ of wood is a stack of split wood measuring 4 feet by 4 feet by 8 feet.” Multiply those three numbers and you get 128 cubic feet — which is exactly how Vermont’s Agency of Agriculture, Food & Markets writes the rule for anyone selling firewood: a cord “is the space that a pile of wood occupies when stacked tightly, with all the pieces pointing in the same direction, that when measured is equal to 128 ft3.” Read that sentence twice, because it measures something surprising: not the wood, but the space the wood takes up when it is stacked neatly. The air between the logs is inside the measurement. That is also why the state does not let sellers invent their own words for a load. “Vermont requires that firewood be sold by the cord,” the guide says, and “The only legal measurement in Vermont is the cord.” Terms like “face cord,” “stovecord” or “truckload” are not allowed there, and the seller “is required by law to provide a receipt for the sale.”
Basis: Vermont Agency of Natural Resources, Department of Forests, Parks and Recreation, “Cordwood”; Vermont Agency of Agriculture, Food & Markets, Weights & Measures, “Guide to Buying & Selling Firewood.” Quotations unchanged, except that the forestry page’s doubled quotation marks around cord are shown here as single quotes; the agriculture guide writes cubic feet as “ft3”. 4 × 4 × 8 = 128 is arithmetic, not a claim by either agency.
A cord of wood is not ready to burn the day it is cut. The same Vermont forestry page describes the wait: “Cordwood needs to be split to an appropriate size and stacked up off the ground for 6-12 months to “season” before being burned.” Seasoning means drying, and drying needs moving air: “To dry effectively, it’s important that your wood pile have access to lots of air flow.” The page even names the finish line — “Cordwood should be burned when its water content has dropped to 15-20%” — and two ways to check it without a meter: cracks on the cut ends, and “a hollow sound when two are knocked together.” Burning wood before it is dry is not just harder; the page warns that “Green wood is not only more difficult to burn, but also very bad for air quality and the safety of your stove and chimney.” So a woodpile is a clock. The stack you build this spring is the heat you get next winter.
Basis: Vermont Agency of Natural Resources, Department of Forests, Parks and Recreation, “Cordwood.” Quotations unchanged.
Firewood also has travel rules, and the reason is passengers. Vermont’s forestry department explains that “firewood may also carry invasive insects and diseases that can kill native trees, decrease property values, and that are costly to manage,” and that this is not a theory: “There are many examples of firewood carrying pests to new places.” The examples it gives are journeys a person made for the wood — “New Asian longhorned beetle infestations developed when firewood was transported from Brooklyn to eastern Long Island, within Ohio, and most likely from Worcester to Boston MA” — and a disease that hitched along: “Oak Wilt, a tree disease that occurs in the central US, was brought to the capital region of New York on firewood.” So Vermont wrote a rule: “The rule states that cut firewood cannot be brought into Vermont without certification that it is heat treated.” It covers exactly the kind of wood people throw in a car trunk — “Vermont’s rule applies to wood for burning cut less than four feet long. It does not apply to chips, pellets, pulpwood, or wood sawn into boards, planks, or beams.” — and the department explains why firewood is the risky one: “Firewood is riskier than other wood products because it is more likely to be produced from unhealthy trees,” and “Unlike sawlogs, which must be processed quickly so they don’t degrade, firewood is often stored for a long time before burning.” The bumper-sticker version, which you may see at a campground: buy it where you burn it.
Basis: Vermont Agency of Natural Resources, Department of Forests, Parks and Recreation, “Frequently Asked Firewood Questions.” Quotations unchanged.
Why measure firewood by the size of the stack instead of putting it on a scale? None of the sources used here says, so here are two ideas, not findings. One is that weight moves. The forestry page says wood is burned when “its water content has dropped to 15-20%,” which means a fresh log and the same log a year later are not the same weight — so a price per pound would change with the weather, and a buyer could pay for water. The other is that anyone can check a stack: a tape measure and three numbers, right there in the driveway, with no scale and no trip to a weighbridge. Both are guesses about a rule that is simply written down as a shape. If you find a source that explains the choice, you have learned something this page could not.
※ A hypothesis is an idea that isn't proven yet.
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