Firewood

A cord of well-seasoned oak delivers roughly 24–29 million BTU — the energy equivalent of about 175 gallons (662 L) of propane. That number anchors everything about managing a firewood supply: species selection, seasoning time, storage volume, and annual quantity all flow from the BTU you actually need to heat a given space. Getting the fuel right before the season starts means the difference between a comfortable winter and a desperate scramble.

Wood species and BTU output

Heat output is determined primarily by wood density. Dense hardwoods pack more combustible material per cord. Softwoods burn faster and hotter for short durations but deliver fewer total BTUs per cord — useful for kindling and fire-starting, but a poor choice for sustained heating.

BTU values per cord (million BTU, air-dried, approximately 20% moisture content):

Species	BTU/cord (MMBTU)	Splitting difficulty	Seasoning time	Notes
Osage orange (hedge)	29–32	Difficult	12–18 months	Highest heat output; sparks heavily; best in enclosed stoves only
Black locust	26–27	Moderate	12 months	Dense, rot-resistant in storage
White oak	24–29	Moderate	18–24 months	Benchmark heating hardwood; long seasoning required
Hickory	24–27	Difficult	12–18 months	Dense, heavy; long-lasting coals
Red oak	24–27	Easy–moderate	12–18 months	Widely available; excellent balance of heat and seasoning time
Sugar maple	24–25	Moderate	12–18 months	Low smoke; popular in Northeast
Beech	24–26	Easy	12–18 months	Good coals; splits cleanly
Ash	23–25	Easy	6–12 months	Shortest seasoning among quality hardwoods
Yellow birch	21–23	Easy	6–12 months	Burns well; pleasant aroma
White birch	18–20	Easy	6–12 months	Lower BTU; widely available
Douglas fir	20–21	Easy	6 months	Common in West; higher creosote risk than hardwoods
White pine	14–17	Very easy	3–6 months	Kindling and fire-starting only; poor heating fuel

Field note

Ash is the most forgiving firewood species for preparedness purposes. It splits easily even when green, seasons in as little as six months, and delivers roughly 90% of oak's heat output per cord. If you are starting a firewood program from scratch with limited lead time, target ash for the current season and oak for the one after.

Cord sizing and what you are buying

A full cord is a stacked pile measuring 4 feet high × 4 feet wide × 8 feet long (1.2 m × 1.2 m × 2.4 m), totaling 128 cubic feet (3.6 m³). This standard includes wood, bark, and air gaps between pieces. Actual solid wood volume is typically 80–90 cubic feet (2.3–2.5 m³) per full cord.

Common variations:

Face cord (rick): 4 ft × 8 ft (1.2 m × 2.4 m) stacked face, but only 16 inches (41 cm) deep instead of 48 inches (1.2 m). A face cord is one-third of a full cord when wood is cut to standard 16-inch (41 cm) lengths. Many sellers use this unit without clarifying it.
Half cord: any configuration totaling 64 cubic feet (1.8 m³).
Thrown cord (loose cord): wood tossed into a truck bed, not stacked. A thrown cord is roughly 180 cubic feet (5.1 m³) loose — it stacks down to about 128 cubic feet (3.6 m³) when properly ranked and measures.

Face cord vs. full cord confusion

A seller offering a "cord" at a low price is often selling a face cord — one-third the volume of a full cord. Always ask: "How many inches deep is the stack?" and measure before accepting delivery. Buying firewood by the full cord, stacked and measured at the drop site, is the only reliable basis for comparison.

Annual firewood needs

Your heating requirement depends on climate zone, home insulation, stove efficiency, and whether wood is your primary or supplemental heat source. These are working estimates for a moderately insulated home.

Primary wood heat (whole-home):

Climate zone	Heating degree days (HDD)	Cords per 1,000 sq ft (93 m²) per season
Cold (Minnesota, Maine, Montana)	8,000–10,000 HDD	2–3 cords
Moderate-cold (Ohio, Colorado, Oregon inland)	5,000–7,000 HDD	1.5–2.5 cords
Mild (Mid-Atlantic, Pacific NW coast)	3,000–5,000 HDD	1–1.5 cords
Southern states	Under 3,000 HDD	0.5–1 cord

A 1,500 sq ft (139 m²) home in Minnesota used as primary wood heat typically burns 4–6 full cords per season. The same home in Virginia burns 2–3 cords. Always add a 25% buffer — one cold winter or a late cold snap outpaces tight estimates. Surplus wood stores into the next season; running short mid-February is not a recoverable error.

If wood is supplemental heat alongside a gas furnace or heat pump, reduce the estimate by 40–60% depending on how often you supplement rather than carry the full load.

Field note

The two-season rule keeps you out of trouble: always have one year's wood dry and stacked, and one year's wood actively seasoning. It takes discipline the first year but becomes automatic after that. If you can only maintain one season ahead, buy commercial split and dried wood to fill gaps — do not burn green wood to make up the shortfall.

Splitting: maul versus power splitter

Most firewood requires splitting before it can season adequately. Whole rounds dry from the outside in; split faces expose interior wood to airflow and cut seasoning time by 30–50%.

Splitting maul technique

A splitting maul weighs 6–9 lbs (2.7–4.1 kg) and uses wedge geometry to force wood apart rather than cut it. Use a 6 lb (2.7 kg) maul for most work; heavier models for very dense hardwoods. A lighter maul swung faster delivers more splitting energy — kinetic energy scales with velocity squared, not linearly with mass.

Set the round on a solid chopping block. A large cross-section log or a rubber splitting block works well. Never split on bare ground — you lose the rebound and drive the maul into soil.
Stand with feet shoulder-width apart, positioned so the maul will arc through the top of the round and continue 4–6 inches (10–15 cm) past it. This means standing slightly farther back than feels natural.
Find a radial crack in the end grain and aim for it. Splits follow the grain; forcing across grain wastes effort.
Grip the handle near the end for maximum arc. Start with both hands high, let the lower hand slide toward the knob as the maul descends.
Swing through the wood — aim for a point 4–6 inches (10–15 cm) below the surface, not at the surface.
For large rounds or knotty sections, split from the outer edges toward the center rather than attacking the middle first.

For crotch pieces and twisted-grain sections, drive a steel splitting wedge with the maul rather than swinging the head directly — it prevents handle cracking and provides more mechanical force.

Hydraulic log splitter

A gas-powered horizontal splitter handles 5–25 tons (4.5–22.7 metric tonnes) of splitting force and reduces the physical labor of splitting a cord from several hours to under one hour. Electric models (5–10 tons / 4.5–9 metric tonnes) are quieter but require grid or generator power. For homesteads burning 4+ cords per year, a splitter represents a moderate investment that recovers quickly in labor savings.

For preparedness purposes, the maul remains the essential tool — no fuel, no maintenance, and no failure points. The splitting maul and axe page covers tool selection, handle maintenance, and head geometry in detail.

Seasoning: timeline and moisture testing

Seasoning is the drying process that reduces wood moisture content from 30–60% (green) to below 20% (air-dry, ready to burn). Below 20%, wood burns cleanly and efficiently. Above 25%, significant energy goes into evaporating water before combustion begins — reducing heat output, increasing smoke, and accelerating creosote deposits in the flue.

Minimum seasoning timelines:

Wood type	Warm, dry climate	Humid climate
Ash, birch	6 months	9–12 months
Maple, beech	9–12 months	12–18 months
Oak, hickory	12–18 months	18–24 months
Osage orange	18 months	24 months

Longer is always better. Oak seasoned for 24 months burns noticeably better than oak at 12.

Accelerate seasoning by:

Splitting immediately after felling — exposed end grain dries far faster than bark-covered rounds
Elevating wood off the ground on pallets or rails so airflow passes underneath
Orienting stacks to face prevailing winds and afternoon sun
Leaving the top of the pile uncovered during dry periods; adding a metal or tarp roof only to shed rain while leaving sides open

Test moisture content with a pin-type moisture meter (inexpensive; available at hardware stores for around $20–40 USD). Insert the pins into a freshly split face — not the cut end, which dries faster than the interior. Below 20% moisture content: ready to burn. Below 15%: excellent. Above 25%: needs more time regardless of visual appearance.

Never burn green wood in a wood stove

Green wood (above 25% moisture content) smolders rather than combusts, produces dense smoke, and deposits creosote at high rates — including the tar-like Stage II creosote and hard-glazed Stage III creosote that require professional removal and can ignite chimney fires. Burning green wood routinely damages the flue and creates a genuine fire hazard. If wood hisses, steams, or is difficult to keep lit, it is not ready.

Firewood storage

Proper storage protects the seasoning investment and prevents moisture reabsorption after drying.

Site selection: - Store wood at least 20–30 feet (6–9 m) from the house or outbuildings to reduce pest and fire risk - Full sun and prevailing wind exposure accelerates continued drying - Do not store directly against a foundation — termites and carpenter ants use woodpiles as staging areas

Stack construction: - Elevate on pallets, 4×4 rails, or purpose-built log racks to allow airflow below and prevent ground contact - Stack bark-side up on the top layer so rain sheds off rather than soaking into end grain - Cover only the top third of the pile with a tarp or metal roofing panel — never the sides; enclosed piles trap humidity from the wood itself and slow the final drying stages - Keep stacks under 4 feet (1.2 m) tall unless braced at the ends with sturdy stakes

Pest control: - Do not stack firewood inside garages or against occupied walls except for a small working supply (2–3 days) - Inspect wood before bringing it indoors; wood-boring beetles and ants overwinter in bark - Rotate stock — use oldest wood first, never letting the back of the pile age into decay

Working supply indoors: Keep 1–3 days of wood in a dry covered bin near the entry point to the stove. This small amount is safe for indoor storage and protects your morning fire routine from ice and rain.

Firewood in the larger energy system

Firewood is a fuel, not a stove. How you burn it determines whether you get the BTUs the species table promises. The wood-heat page covers stove selection, installation clearances, flue sizing, and the daily operating practices that keep combustion efficient and creosote at bay. If you are building toward a low-fuel cooking and heating setup, the rocket stove page covers combustion geometry and how to get the same heat from a tenth of the wood. For fire-starting fundamentals that apply whether you are lighting a stove or a camp fire, fire starting techniques covers the complete skill set.