Protecting Public Health and the Environment.

Better Woodstove Burning Techniques

Smoke from wood burning is a significant source of air pollution and can have serious health consequences. Common health effects from wood smoke include congestion, headaches, and itchy eyes. Wood smoke consists of small airborne particles that can become lodged in our lungs, making breathing difficult and leading to more serious short-term and chronic health problems for certain sensitive populations, especially those with asthma, respiratory or heart conditions, or other illnesses. Children and the elderly are also at risk.

Woodstove operators can control air pollution from wood smoke and improve a stove's performance by learning to use the stove properly and burning correct fuels. Below is a brief description of key phases in the combustion process and operator tips to assist in achieving a cleaner and more efficient burn.

Stages of Burning

  • Evaporation: Before wood can burn, excess water must first be evaporated. The energy required for evaporation is wasted energy, as it could have been used to heat your home instead. Use dried or seasoned wood for a more efficient burn.
  • Emissions: As heat inside the stove intensifies, waste gases (smoke) are released from the wood. Unburned smoke is emitted into the air as pollution or condensed in the chimney, causing creosote buildup. A good supply of oxygen will help burn up or diminish waste gases; conversely, starving a fire of air results in a cooler fire and more unhealthful emissions.
  • Charcoal: When most of the tar and gases have burned, a bed of coal (charcoal) remains; this bed of coals boosts the combustion process when burning larger pieces of wood. Your best bet is to start with a small fire to develop a bed of hot coals. As the coal bed develops and the stove heats up, slowly add larger and larger pieces of wood, stacking them so that air can circulate freely around them. It takes time to build a good coal bed, but the increased amount of heat makes the extra effort worthwhile.

Tips for Better Burning

Minimize woodstove use on high-risk burning days.

The risk of air pollution buildup is highest on days with poor ventilation (stagnant air). Poor ventilation and temperature inversions trap smoke for extended periods of time near the ground, where it hovers around our homes. During this time smoke from residential wood burning can combine with car exhaust, road dust, and industrial emissions to cause air quality to become unhealthy. Smoke from just one poorly burning woodstove can create serious health problems for the family and neighbors. Avoid burning when ventilation is poor. In addition, check DEQ's daily air quality reports to see if burning has been restricted in your area.

Burn only seasoned wood.

Newly cut logs are 50% water. If you burn logs when they are this wet, a high amount of energy is wasted driving off excess moisture, resulting in very poor combustion, increased pollution, and creosote buildup.

The best fuel is seasoned wood, wood that has been split and dried by air for at least 6 months for softwoods or about 1 year for hardwoods. Seasoned wood has a moisture content of about 20% or less. It tends to be dark in color, cracked on the ends, and light in weight, and its bark is easily broken or peeled. If seasoned wood is not available, manufactured logs made of compressed sawdust are another option.

Do not burn garbage in your stove. Plastics, rubber, paint, oil, painted briquettes, charcoal, and glossy and colored paper release toxics when burned and can cause serious health problems for you, your family, and your neighbors.

Prepare seasoned wood:

  • Split wood to help it dry. Wood will dry more quickly and burn best if cut to about 3 1/2 to 6 inches in diameter.
  • Stack wood loosely in alternating layers (crisscross fashion) at least 1 foot above the ground and away from buildings. A sunny, well-ventilated area is best.
  • Cover wood to protect it from the weather. Leave the sides open to breezes.
  • Give it time to reach the 20% or less moisture content required for seasoned wood. This process takes about 6 months for softwoods and 1 year for hardwoods. Think ahead and buy next winter's wood well in advance.

Consider wood heating values

Species Minimum Outdoor Drying Time Heating Value
Million Btu/Air-Dried Cord
Ease of Splitting Sparks
Alder At least
6 months
18-21 medium Easy Moderate
Cedar 6 months 14-20 medium-low Easy Many
Douglas Fir 6 months 19-21 medium Easy Moderate
Madrone 6 months 30 high Difficult Very few
Maple 6 months 19-21 high-medium Moderate Few
Oak 6 months 29-31 high Moderate Few
Pine 6 months 17 medium-low Easy Moderate
White Fir 6 months 17 medium-low Easy Moderate

Inspect and maintain your stove.

Periodic inspection of your stove or fireplace is essential for continued safe and clean burning:

  • Clean chimneys every year to remove creosote buildup and identify potential problems. Ensure the chimney cap is free of debris, and stovepipe angles and bolts are not corroded.
  • Replace the catalytic combustor and baffles every 1 to 4 years depending on use, as they are exposed to very high heat and deteriorate with time.
  • Replace gaskets on airtight stove doors every few years. Gaskets and seals control the location and flow of air into the appliance.
  • Check seams on stoves sealed with furnace cement. Seams may leak and result in heat loss and reduced efficiency.
  • Replace broken or missing firebrick.
  • Keep the floor of your stove clean of debris and ash.

Burn smaller, hotter fires.

Build small, hot fires instead of large, smoldering ones to reduce smoke and emission of smoke-related pollutants. (Hot temperatures burn off waste gases better than cooler fires.) When starting a fire, keep the damper and other air inlets open for 20 to 30 minutes to allow in enough air to fuel a hot fire. Establish a bed of coals before putting large logs into the stove.

Don't bed it down for the night.

Holding a fire overnight is a fire hazard, and because it does not allow an adequate amount of air into the firebox, creates a lot of smoke and creosote. You will pollute the neighborhood, and the smoke can back draft into the house, causing a serious indoor air pollution problem. Let your fire burn out completely and rely on your home's insulation to hold in enough heat for the night.

Watch your smoke signals!

If you're sending up a lot of smoke, chances are you're burning incorrectly. Apart from the half-hour after lighting and refueling, a properly burning fire should give off only a thin wisp of white steam. If you see smoke, adjust your dampers or air inlets to let in more air. Remember: the darker the smoke, the more pollutants it contains and the more fuel is being wasted.

Staff Contacts

Airshed Management Analyst
Pascale Warren
DEQ State Office
Air Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0586

Air Quality Manager
David Luft
DEQ Boise Regional Office
1445 N. Orchard St.
Boise, ID 83706
(208) 373-0550

Air Quality Manager
Shawn Sweetapple
DEQ Coeur d'Alene Regional Office
2110 Ironwood Parkway
Coeur d'Alene, ID 83814
(208) 666-4602

Air Quality/Remediation Manager
Rensay Owen
DEQ Idaho Falls Regional Office
900 N. Skyline Drive, Suite B
Idaho Falls, ID 83402
(208) 528-2650

Air Quality Manager
Philip Hagihara
DEQ Lewiston Regional Office
1118 "F" St.
Lewiston, ID 83501
(208) 799-4370

Air Quality Manager
Melissa Gibbs
DEQ Pocatello Regional Office
444 Hospital Way #300
Pocatello, ID 83201
(208) 236-6160

Air Quality/Remediation Manager
Bobby Dye
DEQ Twin Falls Regional Office
650 Addison Avenue West, Suite 110
Twin Falls, ID 83301
(208) 736-2190

DEQ Resources

More Information

Public Service Announcements

  • Split, Stack, Cover, Store
    This PSA provides four easy steps on how to dry wood for proper use in wood stoves or fireplaces:
    > Split wood to a variety of sizes but no larger than a 6-inch wedge.
    > Stack wood away from a building and off the ground on a pallet with split side down to promote drying.
    > Cover the top of wood with a tarp or woodshed.
    > Store: Allow time for the wood to dry. This can be 6–12 months, depending on the type of wood.
  • Wet Wood is a Waste
    This PSA explains how to use a simple moisture meter to test wood to see if it is dry enough to burn. Moisture meters are available in all sizes and can cost as little as $20. Properly dried wood should have a reading of 20% or less.

Related Pages

Burn Restrictions and Bans

Woodstove Changeout Program

EPA-Certified Woodstoves

Woodstove Replacements and Tax Deductions

West Silver Valley Air Quality Improvement Projects