What are the warning signs of a chimney fire and how do Ottawa firefighters recommend I respond?

A chimney fire is one of the most terrifying and dangerous emergencies that can happen in an Ottawa home, and recognizing the warning signs could literally save your life. The most obvious signs include a loud roaring or rumbling noise coming from inside the chimney (like a freight train or jet engine), visible flames or sparks shooting out of the chimney top, a strong smell of burning creosote that fills your home, heavy black smoke pouring from the fireplace or stove, and extreme heat radiating from the chimney, fireplace, or stove pipe — you should not be able to hold your hand near any part of the system.

Why Chimney Fires Happen in Ottawa

Ottawa's long, cold burning season creates ideal conditions for chimney fires. When you burn unseasoned wood (anything wetter than 20 percent moisture content), run your stove or fireplace at low temperatures during shoulder seasons to stretch a fire through the night, or skip annual chimney cleaning, creosote accumulates inside the flue. Stage 3 glazed creosote — that hard, shiny black coating that builds up on the inside of the chimney liner — is essentially combustible varnish. Once it ignites, it burns at temperatures that can exceed 2,000 degrees Celsius, hot enough to crack a clay tile liner, damage a stainless steel liner, crack surrounding masonry, and potentially ignite framing and structural wood hidden inside your walls. Most Ottawa chimney fires happen in November or early December when homeowners have built up creosote over several months of burning and finally run a hot fire after weeks of cooler burns.

If you suspect a chimney fire is happening right now:

First, call 911 immediately. Ottawa Fire Services will respond to chimney fires as structural emergencies. Do not assume it will burn itself out or that you can handle it alone. A working chimney fire is a life-threatening emergency. While you are waiting for the fire department, evacuate everyone from the house, including pets, and move to a safe location outside and away from the building — do not re-enter for any reason. Close all doors to the room with the fireplace to limit oxygen flow to the fire, but do not close exterior doors that firefighters will need to access. Turn off your furnace if you can do so safely from outside the house — a running furnace can draw additional oxygen into the system and intensify the chimney fire.

Do not try to extinguish a chimney fire with water from inside the house. Throwing water down the chimney will create steam explosions that can shatter the liner, crack the chimney, and blow hot debris out of the top and into your attic. Do not throw baking soda down the chimney — this is a myth with no basis in fire science. Do not try to smother the fire by closing the damper — you cannot effectively seal a chimney from inside, and attempting this could trap dangerous gases in your home.

After the chimney fire is extinguished:

Before you can use your fireplace or stove again, you must have a professional WETT-certified chimney inspector conduct a Level 2 inspection to determine whether the fire has damaged the liner, the masonry, or the chimney structure. Damage that is not visible from above requires inspection from inside the chimney — a cracked liner can be a latent fire hazard that ignites the next time you run a hot fire. Expect this inspection to cost $350 to $600 in Ottawa. If damage is found, you will likely need chimney relining ($2,000 to $5,000 for stainless steel, $4,000 to $8,000 for cast-in-place) before the system can be safely used again. Some fire-damaged chimneys cannot be safely repaired and must be rebuilt, which runs $3,000 to $8,000 for above-roofline rebuilds or $8,000 to $20,000 or more for full-height rebuilds.

Prevention is infinitely cheaper than dealing with a chimney fire. Burn only seasoned hardwood with 15 to 20 percent moisture content — if you are buying firewood, get it from a local Ottawa supplier at least one cord ahead of when you plan to burn it, so it has time to season. Never burn softwood, treated lumber, plywood, or wet wood. Have your chimney professionally cleaned and swept by a WETT-certified chimney sweep every year — twice yearly if you burn more than 4 cords per season. Most Ottawa homeowners should schedule their annual sweep in early fall (September or early October) before the heavy burning season begins. Do not run fires so cool that smoke is pouring out of the chimney — this indicates incomplete combustion and maximum creosote production. If you are running your fireplace or stove at such low temperatures that you need to keep heat down, consider using it only for ambiance rather than as your primary heating source, or upgrade to a more efficient appliance. Install and maintain working carbon monoxide detectors on every level of your home — a chimney fire or a malfunctioning appliance can introduce deadly carbon monoxide into your living space.

When you are ready to hire a professional WETT-certified chimney sweep for your annual cleaning or a post-fire inspection, you can browse experienced chimney technicians through the Ottawa Construction Network directory at justynrookcontracting.com/directory — they understand Ottawa's climate and the urgency of proper chimney maintenance before the cold season begins.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Apple HVAC and mechanical
• JC Carpentry
• East Coast Sheet Metal Inc
• Ottawa Demolition Corp.
• BFI Renovations