FAIRBANKS — Q: How long does it take to season firewood?
A: Although it’s hot and sunny in the Interior this week, winter is never far from the mind. And these long summer days are the ideal time to think about acquiring, splitting and storing firewood for Alaskans with wood-burning appliances. Doing these steps toward the beginning of summer is helpful for wood that will be burned during the coming winter. After the first few months of summer pass, many residents collect, split and stack wood for winters further down the line.
It’s important to plan ahead for firewood splitting and storage so it has sufficient time to dry out, or “cure,” to a moisture content of 20 percent or less. Dry wood both produces more heat when burned than a comparable amount of wet wood — saving you money — and burns more cleanly. In fact, burning wet wood produces excess smoke and PM 2.5-sized particles, which disperse into the air and can be harmful to health.
How long it takes to dry wood depends on the species of wood, when you harvest it, how you cut it and how you store it. CCHRC staff tested various methods of drying wood and found it is possible for wood to dry rapidly during a single summer — no matter when it’s harvested — but takes quite a bit longer during the shoulder seasons or winter. No matter what wood or method you use, firewood harvested in the fall won’t be fully cured by that winter.
In our study, split wood harvested in the spring took anywhere from six weeks to three months to dry during summer, depending on the storage method. Split birch and split spruce, for example, dried in just 1.5 months when stored in a simulated wood shed or left uncovered. In general, the fastest way to dry split wood was by storing it in a woodshed or leaving it uncovered, although uncovered wood is at the mercy of the weather and could be wet again by fall. When stored under a tarp, the wood took three months to cure.
Unsplit wood, on the other hand, didn’t cure during the summer in any storage scenario. Though it neared 20 percent moisture content by the end of the summer, it required another summer to reach a full cure.
Firewood harvested in the fall didn’t cure by springtime no matter how it was cut or stored. While it dried out somewhat in a wood shed (to between 30 percent and 40 percent moisture content) some samples got wetter under a tarp during the winter.
Several other factors should be considered when seasoning your wood. Spruce and birch tend to dry more quickly than aspen. And your drying times also will vary based on exposure to sun and air circulation (the more, the better).
The good news is it’s possible to harvest firewood in the spring and cure it in a single summer — so you can stay cozy and burn cleanly in the winter.
The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.
Ask a Builder articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, contact us at email@example.com or 457-3454.