Firewood⎜Types, Uses, Seasoning, Storing, Cords, Facts

Firewood is a renewable heating energy resource.

Carefully managed, a five acre wood lot can give firewood for a 1500 square foot house for a lifetime.

Many homesteaders use wood heat as the primary source of heat in their home.

Having heated or supplemented heat with firewood myself for well over 20 years, this is an article based upon practical experience.

In this article we will look at:

Types of firewood
Uses of firewood
Seasoning firewood
Storing firewood
Measuring firewood
Facts about fire

After reading this article you will be well on your way to being an intelligent user of firewood!

Firewood Types

There are two basic types of firewood. They are known as hardwood and softwood.

The difference between hardwood and softwood is the density of the wood.

Hardwood is more dense than softwood. The more dense the wood, the more heat the wood gives off.

The less dense the wood is the faster the wood burns, but no long lasting bed of coals is produced.

Examples of hardwoods are Maple, Oak and Ash.

Examples of softwoods are Birch, Pine and Spruce.

Ash is considered by many to be the best burning wood. It gives a steady flame and strong heat output.

Birch gives a strong heat output but burns up quickly.

I have added a chart giving the heat output of several different varieties of wood, both hardwoods and softwoods.

After looking at over a dozen different websites that had this type of information on them, I could not find any two websites that agreed on the heat out put of many of the different varieties of trees.

Some website’s information differed by more than one million BTU of heat output per cord for some of the wood species!

So the values I will give are values found in my research.

But as I have said, it is easy to find different values, some higher and some lower for the varieties of wood I listed.

Wood Table⎜Heat Recovery Of Various Species

Species of trees for wood heat	Density at 20% moisture content in pounds/cu. ft.	Average wt. of 85 cu. ft. at 20% moisture content in lbs.	Possible recoverable heat units in millions of BTUs	Available heat at 80% efficiency in millions of BTUs (good wood stoves)
Hickory	50.9	4,327	27.7	22.2
Apple	48.7	4,140	26.5	21.2
White Oak	47.2	4,012	25.7	20.6
Sugar Maple	44.2	3,757	24.0	19.2
Red Oak	44.2	3,757	24.0	19.2
Beech	44.2	3,757	24.0	19.2
Yellow Birch	43.4	3,689	23.6	18.9
White Ash	43.4	3,689	23.6	18.9
Hackberry	38.2	3,247	20.8	16.6
Tamarack	38.2	3,247	20.8	16.6
Paper Birch	37.4	3,179	20.3	16.2
Red Fir	34.9	3,155	22.3	17.8
Cherry	36.7	3,120	20.0	16.0
Elm	35.9	3,052	19.5	15.6
Black Ash	35.2	2,992	19.1	15.3
Jack Pine	31.4	2,669	17.1	13.7
Norway Pine	31.4	2,669	17.1	13.7
Lodgepole Pine	30.7	2,610	17.5	14.0
Hemlock	29.2	2,482	15.9	12.7
Black Spruce	29.2	2,482	15.9	12.7
Aspen	27.0	2,295	14.7	11.8
White Pine	26.3	2,236	14.3	11.4
Balsam Fir	26.3	2,236	14.3	11.4
Grans Fir	25.4	2,160	16.7	13.4
Cottonwood	24.8	2,108	13.5	10.8
Basswood	24.8	2,108	15.5	12.4
N. White Cedar	22.5	1,913	12.2	09.8
*Equals 1 cord, 4' X 4' X 8", of stacked wood				Compiled information from Univ. of MN and Univ. of ID

Hardwoods

Hardwood species are all deciduous trees, trees with leaves.

These trees are more common in the Eastern U.S. Hardwood Forests.

But there are places in the West and Mid-West U.S. that some of these species may be found.

When we lived in Tennessee we burned a lot of Oak in our airtight fireplace insert.

The Oak gave very good heat that could be felt some 45 to 50 feet away from the fireplace insert when the blowers were on.

Our fireplace insert was installed inside a special made, insulated, double wall metal box designed for that particular fireplace insert.

The house we placed it in did not have a fireplace.

This metal double walled and insulated box had a place on top where an insulated chimney, like the chimneys that exit the roof from wood burning stoves, was attached.

In the 4 years we lived there the Oak burned hot enough that we never had to have the chimney swept by a chimney sweep.

The Tennessee house was located on the Cumberland Plateau about 7 miles north of Crossville, Tennessee.

It was a little over 1800′ elevation there and it was not unusual for it to sleet on July 4 each year so having a source of wood heat was very nice.

Softwoods

Most softwood species are conifers, trees with needles instead of leaves.

However, there are deciduous softwoods such as Aspen, Birch, Basswood and Cottonwood.

The best conifers to burn for heat, Tamarack, Red Fir and Lodgepole Pine are found primarily in the mountainous regions of the Western U.S.

Our homestead in the Idaho mountains has a lot of Lodgepole Pine.

We have found it to be satisfactory as a wood to burn in our wood burning stove.

Each day we have a hot fire, where the thermometer on top of the wood stove reads 250 degrees F for 1 to 2 hours.

This keeps the creosote from attaching to the inside of our double wall stove pipe.

We are at about the 2500′ elevation and some 45 to 50 miles as the crow flies from the Canadian border.

Even when the thermometer drops into the minus degree F range we have found the Lodgepole Pine to be a satisfactory wood to burn for heat.

Can I Burn Wood From Pallets

Wood from pallets can be burned provided the wood is not treated with methyl bromide, a bug killer.

Pallets treated with methyl bromide are supposed to be labeled with the initials MB.

Chep Pallets are pallets that are painted blue and have Chep in white letters on them.

You should not burn these pallets in a wood stove because of the paint.

The burning of any painted, stained or pressure treated wood in a wood stove or fireplace releases harmful chemicals into the air.

These chemicals can affect the life of stove pipes and insulated chimney pipes.

Uses Of Firewood

If you have a wood lot with a variety of species of trees here is how to manage your wood pile.

Save the more dense fuel, the hardwoods, for the colder months of winter.

Use the less dense wood, softwoods, for starting fires and to use during the fall or spring when you do not need as much heat as needed in the cold winter months.

If you do not have a mixture of hardwoods and softwoods available, use the available wood with the highest BTU per cord during the cold winter months.

Save the woods with the lower BTU per cord to start fires or to burn in the fall and spring when it is not as cold as in the winter.

Wood Lot Management

In managing a wood lot it is best to first use up all the downed dead wood that is still sound.

Avoid using downed dead wood that is rotten. It will be hard to burn and give off very little heat.

Once all the downed dead wood that is sound is used up, then start using the standing dead wood next.

Once the standing dead wood is all used up, the next trees to use are those that are dying.

These can usually be identified by there having some branches with green leaves and some dead branches without leaves on them.

If the tree is a conifer, there will be branches with green needles and branches with dead limbs or brown needles.

After using all dying trees, the next trees to harvest are the mis-shapen trees.

These would include trees with twisted trunks and trees with splits where two relatively equal sized sections are growing side by side.

Table⎜Estimating Number Of Cords Per Tree

DBH*	Cords Per Tree	No. Trees To Make A Cord
4"	0.01	67.00
6"	0.04	23.00
8"	0.09	10.50
10"	0.17	5.80
12"	0.28	3.50
14"	0.41	2.40
16"	0.58	1.70
18"	0.70	1.30
20"	1.00	1.00
22"	1.20	0.82
24"	1.50	0.67
26"	1.80	0.54
28"	2.20	0.46
30"	2.50	0.40
DBH = diameter outside bark at 4.5" above ground		Univ. Idaho Extension Service Data

Then you go through the wood lot and harvest the very large trees that are crowding out new tree growth.

As trees die or fall to the ground, you would use these trees as you find them after harvesting the downed and standing dead trees.

Carefully managed, a five acre wood lot should provide firewood to heat a 1500 square foot house without running out of trees.

If the house was larger than 1500 square foot the wood lot size would need to be correspondingly larger.

You would want a wood lot with either a mixture of trees or mostly the best variety of trees for firewood in your area of the country.

A wood lot with only one variety of tree, especially if it was a tree that did not give a lot of heat per cord of wood, is not the ideal wood lot.

That type of wood lot would need to be larger than if it had a variety of trees.

If you do not have a wood lot but live near a State or Federal forest you can purchase a permit which allows you to harvest wood from that State or Federal forest.

The cost of a permit is very reasonable.

The Ranger Station can fill you in on the details and rules of harvesting firewood.

Seasoning Firewood

Seasoned firewood is dry firewood. When cut down, growing trees can have a moisture content of 40% to 45%.

Standing dead wood and downed dead wood can have a moisture content of 35% to 40%.

When the water content is above 30%, water will bubble from the ends of the wood when placed in a fire.

Seasoned firewood should have a moisture content of less than 20%.

Wood with a moisture content above 20% may burn, but it is hard to start it burning and difficult to keep it burning.

So seasoned wood is dry firewood with a moisture content of less than 20%.

hand splitting wood with an ax — Hand splitting wood with an ax

Remove the branches from the cut or downed trees.

Then cut the wood into the proper lengths for your wood burning stove.

Next split the wood into sizes easy to handle.

This usually means splitting each log into halves or quarters. It should be easy to hold a piece of wood in one hand.

Stack the wood into rows with some space between each row.

Probably the most popular method of splitting firewood is to use a gas powered hydraulic wood splitter.

Usually ranging in size from a 25 ton splitter to a 35 ton splitter.

Yardmax (link to read reviews on Amazon) makes gas powered hydraulic log splitters.

A good all around choice for a log splitter is the Champion 25 ton gas powered hydraulic log splitter (link to read reviews on Amazon).

A log splitter like this would handle most homestead wood splitting jobs.

Remember, it is best to split wood right after cutting down the tree and cutting it into the proper length for your wood burning stove.

If you wait until the cut logs are seasoned, the wood is harder to split.

Besides, the wood seasons faster when split.

If you have a 20 ton splitter and wait until hardwood is seasoned, that 20 ton splitter will strain to split some seasoned hardwoods.

A larger sized splitter would be needed to split seasoned hardwood easier and faster.

Some prefer to stack the wood into circular piles instead of rows.

Others like to stack one row of wood with the pieces running side by side and then the next row of wood with the pieces running front to back.

If wood is split and stacked by the end of March, it should be seasoned by the first of October.

Stack the firewood where it will not be rained on while seasoning.

Firewood dries quicker if it is not covered and if it is not touching the ground.

This allows the sun and wind to get to it better and dry it quicker.

If the cold weather comes earlier than expected, it can help wood to dry if it is brought into the house a couple of days before you plan on burning that wood.

If you stack split firewood out in the open, stack it where the bark is on the top surface of the wood.

This helps shed rain and helps keep the wood from absorbing water that delays seasoning.

How To Know If The Firewood Is Seasoned

Over time the color of the wood will fade. Wood that is split drys or seasons faster than un-split wood.

As wood dries it looses moisture content and becomes lighter.

As it dries, wood becomes harder and more difficult to split.

A point comes in the drying or seasoning process where the bark begins to separate from the wood.

As the moisture content of the seasoning wood approached 20% and lower, cracks will appear in the sawn ends of the wood.

If you take two pieces of seasoned wood and hit them together you hear a crack. If the wood is not yet seasoned you will hear a thud.

Can Firewood Become Too Dry Or Too Seasoned

If wood has been stored in a hot dry place or if the firewood is kiln dried, it can become very dry.

Very dry wood will burn up faster than seasoned wood will burn up.

Mix the very dry wood with regularly seasoned firewood when burning very dry wood in a wood stove.

This will keep the very dry wood from burning up so fast.

What Is The Cleanest Wood To Burn

The cleanest wood to burn in a wood stove is the hardest wood available in your part of the country.

The hardest wood available is the wood with the highest BTU rating, even if it is a softwood like Tamarack or Red Fir.

To burn clean the wood must be well seasoned.

Storing Firewood

If firewood is stored against a house for a log period of time, it is possible to introduce pests such as termites into the house.

If you live in an area that is subject to wildfires, storing wood against the house is not advised.

Burning embers from a wild fire can be carried by the wind for well over a mile.

If those burning embers were to lodge in a wood pile stored against your house the result could easily be a fire that would burn down the house.

Some people who live in areas subject to wild fires, will wait until the first snow fall of late fall and then move firewood beside the house.

The preferred method of storing firewood is to have a wood shed with a floor to keep the wood off of the ground.

The sides and back should be open and it should be located about 30 feet from the house.

Firewood stacked in the open should have a cover on the top but not the sides.

If the sides are covered it will not season because moisture will be trapped in the wood.

How Long Will Seasoned Firewood Store

Season the firewood for 2 or 3 years inside of a dry storage such as a wood shed.

If the wood is not in contact with the ground, it can literally last for decades.

Measuring Firewood

The common measure of firewood in the U.S. and Canada is the cord.

A cord is the amount of wood it would take to make a stack 8′ long, 4′ wide and 4′ high or 128 cubic feet of space.

Because the firewood is stacked, it is not a solid 128 cubic feet of space.

There will be places for air to circulate between the pieces of stacked firewood.

Sometimes firewood is sold in what is called a Face Cord.

This is a stack of wood that is the equivalent of being 8′ long, 4′ high but only 16″ deep.

This equals 1/3 of a cord and is sometimes called a rick of wood.

The most common length of firewood is 16″ long.

This length of firewood will fit in most wood stoves rated to heat 1500 square feet or more.

Depending upon the species of wood, a cord of unseasoned firewood can weigh up to 5,000 pounds.

A 8 foot long pickup truck bed would have to be piled uniformly to a height of 5 foot above the pickup bed’s floor to carry an un-stacked cord of wood.

An un-stacked cord of wood can take up to 200 cubic feet of space.

Pickup truck with about a cord of split firewood

The average pickup truck without adding side walls on it can only carry a 1/2 cord of wood.

If someone comes to deliver a cord of wood and they show up in a pickup truck that is only a half-ton truck and it does not have side walls on the bed, they are not carrying a full cord of wood!

Even with side walls the pickup would need to be at least a 3/4 ton pickup with at least 3/4 ton helper springs on the back to be able to deliver a full cord of wood.

How many pieces of wood are there in a cord?

A face cord, or rick, contains between 220 to 240 pieces of wood on the average.

A face cord is 1/3 of a cord if the wood is 16″ long.

So since it takes 3 face cords or 3 ricks to equal a full cord there should be about 660 to 720 pieces of wood in a cord.

How much does a pine tree weigh?

A 50′ pine tree that is 12″ in diameter near the ground can weigh more than 2000 pounds.

An 80 foot Oak tree with a 24″ diameter near the ground can weigh more than 20,000 pounds.

Red Oak weighs about 45 pounds per cubic foot.

This is helpful information when loading a pickup truck or trailer with firewood.

How Long Will A Cord Of Firewood Last

There are several variables that determine the answer to this question.

Is the house that is referred to by Wood Stove Manufacturers as an ideal or standard house?

How big is the house and how cold is it outside?

Is there wind blowing or is it calm outside?

Where in the house is the wood stove placed and is it the proper size for the house?

The often quoted Rule of Thumb for how long a cord of firewood will last is that it takes 5 cords of firewood to heat a 1500 square foot house for one winter.

If cold weather lasts 4 full months, that is an average of 1 1/4 cords of firewood per month.

If the house is not the ideal or standard house or if the house is larger than 1500 square feet it can take more than 5 cords of wood to heat that house during cold weather.

If the wood stove is not properly placed in the house or if it is not properly sized for the house, it will take more than 5 cords of wood to heat the house during cold weather.

If the house is smaller than 1500 square feet and the house is an ideal or standard house, it can be heated with less than 5 cords per cold weather with proper wood stove size and placement.

Facts About Fire

Can a wood stove fire burn without oxygen?

No it can not burn without oxygen.

You can demonstrate this by lighting a candle and putting a clear glass upside-down over the candle without the glass touching the flame.

You will see the flame slowly extinguish as it uses up the oxygen that was trapped in the glass.

Fire is really a chemical reaction. Fire creates light and heat from oxygen and fuel.

Air at sea level contains 21% oxygen. A fire needs at least 16% oxygen to burn.

As the fuel burns, it reacts with oxygen releasing heat and making combustible products such as gasses, embers and smoke.

This chemical process is called oxidation.

Fire’s chemical reactions are self-perpetuating. The flame’s heat keeps the fuel at the ignition temperature.

This allows the fire to keep burning as long as there is fuel and oxygen present.

A Method Of Reducing Creosote In Chimneys

Because creosote buildup in stove pipes and chimneys can cause chimney fires it is important to remove creosote buildup each year.

This is commonly done by calling a chimney sweep or as a DIY job using a chimney brush and connecting rods to brush out the chimney and stove pipes.

What do you do if there happens to be crusty or tarry creosote that does not want to come off with the chimney brushing?

One method is to burn aluminum cans in a very hot fire.

This helps crusty or tarry creosote to flake off and fall down into the fire box of the wood stove. (www.hunker.com)

Here is how to do it. Build a very hot fire.

The flue temperature should exceed 250 degrees F. A thermometer that attaches to the stove pipe is helpful here.

Once the fire is very hot, add a few aluminum cans to the fire.

Go outside and check the chimney smoke. Heavy smoke is a sign the creosote is coming off.

Use a small amount of wood and refill the fire box often. A small hot fire is better than loading up the fire box with wood.

As the aluminum cans burn in this very hot fire, they release manganese from the aluminum.

The manganese causes the crusty and tarry creosote to break down into flakes and powder.

Some of the flakes and creosote powder will fall down into the fire box to be cleaned out the next day after the fire box is cold.

If the stove pipe has elbows in it some will be caught in the elbows.

The next day you will need to again brush out the chimney pipe and stove pipes.

Be sure to clean out any elbows by removing and brushing to clean out creosote collected there.

Using this method described above, a very hot fire is defined as a fire that raises the flue temperature to between 250 and 275 degrees F, the temperature at which creosote can be removed by the manganese and heat.

This temperature is well below the temperatures reached if there was a chimney fire.

It is not uncommon for a chimney fire to reach blowtorch temperatures of 2000 degrees F.

In a pre-fabricated metal chimney such as the stove pipe and insulated chimney pipe used in wood burning stove installations, a chimney fire can cause the metal to warp and twist.

After a chimney fire, it is necessary to have the entire chimney, from the top of the wood stove all the way out to and including the chimney cap professionally checked.

All damaged portions of stove pipe and chimney pipe must be replaced before using the wood stove again.

It is a good idea to have Chimfex sticks (link to read reviews on Amazon) available to stop a chimney fire before it gets out of hand.

We have good friends who used 2 Chimfex sticks to save their house when they had a chimney fire one winter.

On this site you can read more about chimney’s at “Wood Burning Stove Chimneys, An Informative Buyer’s Guide.” where I go into detail about chimney’s.