Douglas fir firewood: BTU, weight and seasoning

Heat per cord

Douglas fir is a softwood. At 20% moisture, a full cord holds about 19.1 million BTU of heat (20.2 gigajoules). Wetter wood gives less, because part of the heat goes into boiling off the water.

That ranks Douglas fir 460th of the 558 species in our tables, from the hottest down.

Weight and density

A full cord of seasoned Douglas fir (20% moisture) weighs about 3,020 lb (1,370 kg). Freshly cut, the same cord weighs about 4,110 lb (1,870 kg): the difference is water you don't want to burn.

Its specific gravity, a measure of density, is 0.51. Denser wood packs more heat into each cord.

Seasoning time

Split and stacked off the ground, Douglas fir needs at least 12 months to dry to about 20% moisture.

Wood dries faster once it is split and stacked with air around it. A moisture meter on a fresh split face tells you when it is ready.

How it burns

• Ash: moderate
• Coals: moderate
• Burn time: moderate

We rate Douglas fir 2 out of 10 as firewood: it burns, but denser species give more heat for the same work.

Similar firewood

Other species to compare with Douglas fir:

• Silver maple: 19.3 million BTU per cord
• Striped maple: 18.8 million BTU per cord
• Black ash: 19.9 million BTU per cord
• Black cherry: 20.4 million BTU per cord

Where it grows

Western North America

Where these numbers come from

The heat and weight figures come from our firewood tables, worked out the same way for every species at 20% moisture. See how we calculate them.

Questions