The sweet gum tree, scientifically known as Liquidambar styraciflua, is a common hardwood found across the eastern United States. While it is a legitimate source of fuel, its quality as firewood is generally considered mid-grade, offering acceptable heat output but presenting significant challenges during processing. Understanding its specific properties is the first step in deciding whether this wood is worth the effort for your heating needs.
How Sweet Gum Compares to Other Firewood
Sweet gum occupies a middle position in the hierarchy of firewood quality, falling between premier hardwoods and softer, less dense species. The heat output for properly seasoned sweet gum ranges from approximately 20.6 to 21.3 million British Thermal Units (BTUs) per cord. This energy content is respectable and places it above woods like cottonwood or silver maple, which have lower BTU ratings.
However, it does not reach the energy density of top-tier hardwoods such as hickory or oak, whose BTU values are considerably higher. This difference means you need a greater volume of sweet gum to generate the same sustained heat as a cord of denser wood. Sweet gum is therefore best categorized as a decent secondary firewood, often used to supplement a primary stack of higher-quality, slower-burning species. Its performance is often compared to woods used for shoulder season fires when extreme heat is not required.
Preparing Sweet Gum: Splitting and Seasoning
The greatest obstacle in utilizing sweet gum for fuel is the physical labor required to prepare the wood. The species is notorious for being extremely difficult to split, a characteristic directly linked to its unique wood structure. Sweet gum possesses an interlocking or spiral grain, where the wood fibers are woven and twisted together rather than running straight down the log.
When struck with a splitting axe or maul, the wood tends to tear and shred rather than cleave cleanly along the grain lines. This resistance to splitting can make manual processing frustrating and highly inefficient. For this reason, many experienced woodcutters recommend using a hydraulic splitter, which can overcome the structural integrity of the tight grain. It is also widely advised to process the sweet gum rounds while they are still green, as the wood becomes even harder and more resistant to splitting after it begins to dry and twist.
Beyond the difficulty of splitting, sweet gum requires a considerable amount of time to reach an optimal moisture content of below 20%. Green sweet gum has a high initial moisture content, sometimes nearing 79%, which is relatively high for a hardwood. This water must evaporate before the wood will burn cleanly and efficiently.
A typical seasoning period for sweet gum is at least one year, and often closer to 18 months, depending on the climate and storage conditions. Proper seasoning involves splitting the wood into smaller pieces, stacking it off the ground, and ensuring good air circulation to facilitate the drying process.
Characteristics of the Sweet Gum Burn
Once properly seasoned, sweet gum wood ignites easily and burns with a good, hot flame. The wood is characterized by a fast burn rate, making it excellent for quick fires that rapidly increase temperature. This rapid consumption, however, is a drawback for long-duration heating.
Sweet gum does not produce long-lasting coals necessary for maintaining heat overnight. The fire tends to die down quickly, leaving behind a substantial volume of ash that requires frequent cleanout. Furthermore, the wood tends to pop and spark while burning, even when fully seasoned, due to its resin content. This sparking necessitates the use of a fireplace screen or closed doors to prevent fire hazards.