Firewood safety | Woodlot Association of Manitoba

Buy locally, burn cleanly, burn safely

A safe wood-burning system consists of:

a safety-certified stove, fireplace or furnace (CMHC Wood Heating Options)
the right type of chimney for the appliance (CMHC The Chimney)
a system design that avoids safety compromises (CMHC Installation Checklist)
reliable advice on safe installation (CMHC Installation of Wood Stoves) or preferably, installation by a qualified professional. Look for retailers, installers and chimney sweeps who are WETT certified under the Wood Energy Technical Training program.

For the complete CMHC Guide:

Reminder: Always check with your local building inspector for specific installation requirements.

The air around you

Backdrafting: In the winter, we close up our homes and fire up the wood stove or fireplace. At the same time, we run kitchen and bathroom exhaust fans that pump air out of the house. As a result, the air pressure indoors falls below the air pressure outdoors, and the house becomes depressurized. Pressure is balanced as fresh outdoor air is drawn into the house through available openings, such as cracks and gaps around windows, doors, and small openings in the building structure… and down the chimney. If you have ever opened the damper before lighting your fireplace and felt the big wash of cold air come into the living room, you have encountered what’s known as backdrafting.

Combustion gases: The problem with backdrafting is that gases from combustion will spill into the house instead of going up the chimney. The smouldering embers of a dying fire, for instance, can release high concentrations of carbon monoxide (CO), a colourless, odourless and extremely toxic gas. This happens because, when a fire is burning down, little heat is being released to carry the gas up the chimney. If you open the firebox doors when the house is depressurized, you may be releasing carbon monoxide directly into the house.

More fresh air: A fireplace fire can require about five times as much air as most houses need for liberal ventilation. To be safe, a positive source of outside air should be supplied to all fireplaces and wood stoves to bring in enough fresh air for efficient burning. This can be provided by installing an outside air vent or opening a window when the fireplace or stove is being used. To keep smoke from entering the room, turn off kitchen and bathroom exhaust fans and close the registers of forced air heating systems which are near the fireplace.

For air safety: Install smoke detectors on every floor of your home. Standard smoke alarms are suitable for detecting combustion spillage from wood furnaces and boilers. Change and test batteries at least twice a year. Carbon monoxide (CO) alarms should be used with fireplaces and wood stoves, and installed near the fuelwood appliance. CO alarms are sold in hardware and electronic stores. Buy one certified to UL2034 or CAN/CGA6.19 standards.

Simple safety measures

Keep a fire extinguisher near your fireplace or wood stove and make sure everyone in your household knows how to use it in the event of fire.

Equip the house with fire-warning devices such as smoke and carbon monoxide detectors.

Keep combustible materials such as carpets, furniture, paper, logs and kindling a safe distance from a wood stove or fireplace hearth.

Use only enough fuel to keep the fire at the desired temperature. Avoid “roaring” fires. They can start chimney fires from soot and creosote deposits in the flue.

Do not use gasoline or other flammable liquids to kindle or rekindle a fire because the flammable vapours can explode. Never use fuels near a fire; explosive vapours can travel the length of a room.

Keep the damper open while the fuel is burning to provide for efficient burning and to prevent accumulation of poisonous or explosive gases.

Never burn Christmas tree greens in your fireplace or stove They cause many sparks when burning and can ignite a chimney fire.

Discard newspaper pages with coloured ink before using newspaper for kindling. The coloured inks contain lead and can produce toxic gases.

Do not use coal, charcoal or polystyrene packaging in a fireplace unless the fireplace is designed to handle the excess heat and smoke which occurs when burning these materials.

Do not treat artificial logs (made from sawdust and wax) the same way you treat real wood logs. Use only one at a time. If you use more, they can produce too much heat for some fireplaces to withstand.

Keep children away from the fire because their clothing can easily ignite. Warn the entire family about this hazard.

Be sure that all ashes have thoroughly cooled before you dispose of them. Put ashes in a lidded metal container to prevent a possible fire, and provide a sturdy place to store them.

Some stoves and furnaces are specifically designed to accommodate overnight burning, but never leave a fireplace fire unattended. Ensure it is extinguished before you go to bed or leave the house.

If you have a chimney fire:

Call the fire department immediately.

If all the stovepipe joints are tight and no other appliance is connected to the same flue, close all openings and draft controls if you have an air-tight stove. Close the stovepipe damper in a non-air-tight stove.

You can attempt to cut off the air supply to a fireplace by using a wet blanket or sheet metal to seal off the fireplace opening. Be careful since a strong draft can make this difficult and dangerous. Use only non-combustible materials.

If you have a leaky stove or fireplace you may have to wait for the fire to burn out.

Get everyone out of the house, and put them to work watching for sparks or signs of fire on the roof or nearby. One adult should stay in the house to check the attic and upper floors for signs of fire.

Discharge a class ABC dry chemical fire extinguisher or throw baking soda into the stove or fireplace if the chimney is not sound or there is a danger of the house or surroundings catching on fire. The chemical travels up the chimney and often extinguishes the flame.

Throwing water in a stove will cause the metal to warp, but if it’s a choice between the house or the stove, use water.

Check the chimney after a fire. A chimney fire can range from 2000-3000⁰F (1100-1650⁰C) which is hot enough to cause deterioration of metal or cause masonry to weaken. Metal chimneys can deteriorate after 2 or 3 fires

If a chimney fire occurs once, chances are that it will occur again. Find the cause.

A problem with frequent chimney fires is the possibility of the framing catching on fire. The ignition temperature of new house framing is about 500⁰F (260⁰C). Over a period of years, as this wood is repeatedly heated by chimney fires, the wood will ignite at a much lower temperature.

Fire safety inside your home is important, but so is safety outside. The FireSmart Manual 2011 is a good guide to protecting your house and buildings from fire.

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