A renewed interest in firewood to offset higher home heating costs has led to a shortage of properly seasoned wood, forcing some homeowners to burn “green” wood. This has caused a great deal of concern to Island fire brigades and insurance companies because burning unseasoned fuelwood can create significant fire hazards.
“Freshly cut wood has a moisture content of about 80 per cent, so it must be dried or "seasoned" down to around 20 per cent before it can be safely burned,” stated Ken Mayhew, Forest Information Officer with the PEI Department of Environment, Energy and Forestry. “Wood with a moisture content higher than 25 per cent is considered to be “green” or "unseasoned” and should never be burned in a fireplace or wood stove because it can dramatically increase the chances of a serious chimney fire.”
Mr. Mayhew pointed out that there are many different factors involved in getting the best and safest heat from fuelwood, but basically, the heat content is a combination of wood density and moisture. He explained that wood moisture has two components - natural wood resins and water. As seasoned firewood heats up in the stove, these resins emit combustible gases which can account for as much as half of the fire’s heat output. However, when green or wet firewood is burned, this heat starts by boiling off the water first, and this lowers the fire’s temperature and prevents the wood gases from igniting and releasing their heat value.
If the wood gases are not burned efficiently, they escape up the chimney, taking their heat value with them and creating heavy creosote formation. Creosote is the product of wood smoke, low burning temperatures, and high wood moisture content, and can be a serious hazard for homeowners who burn green wood. Wet or unseasoned wood greatly increases the accumulation of creosote and, when it builds up in a flue or chimney, it can ignite, causing serious fires.
Most people prefer to burn species such as sugar maple and beech and, while they do have a high heat content per cord, they must be properly seasoned before use. Consumers are often surprised to learn that burning unseasoned maple or birch produces as much creosote as low heat value species such as fir, pine or poplar.
“Burning firewood is an Island tradition and can be quite effective if homeowners use the proper precautions,” said Mr. Mayhew. “In addition to using well-seasoned wood and using a properly-installed furnace, homeowners should regularly build a hot roaring fire to reduce the formation of creosote and have an annual chimney cleaning to reduce any buildups.”
Island contractors provide high quality firewood but proper seasoning takes time. So plan ahead, because next year’s burning season is closer than you think! For more information, visit the Fuelwood Information for Consumers Website: www.gov.pe.ca/go/fuelwood.