Roaring flue, or a quiet fire you missed? What to do now

A roar in the flue? What to do if a chimney fire is burning

If you suspect a chimney fire, get everyone out of the building and call 911 from outside. Do not climb onto the roof, pour water into the fireplace or delay leaving to adjust doors or controls. Stay out until emergency responders permit re-entry.

Do not return for belongings or attempt to extinguish a chimney fire yourself. Get clear of the building, call emergency services and follow their directions. Operating doors or controls should not delay evacuation.

Let the firefighters handle it, and follow their instructions about when it's safe to go back inside. Once they've cleared the house and the chimney, the next job is finding out what the fire did to the flue.

What a chimney fire is

Creosote is the fuel. It's the deposit wood smoke leaves on the flue walls, and a chimney fire starts when it gets hot enough to ignite. A thick coat of crunchy or glazed creosote is a lot of fuel sitting right above a fire, and a hot fire or a burst of flame from dry paper or kindling can set it off.

Some chimney fires are loud and dramatic. Others burn slowly and quietly, without enough air to roar, and the homeowner has no idea anything happened until someone looks up the flue. Both kinds can reach very high temperatures inside the chimney.

That heat is what does the damage. Clay flue tiles can crack from the sudden heating, mortar between tiles can fail, and heat can pass through gaps to the wood framing near the chimney.

Metal parts suffer too. Dampers can warp so they no longer seal, and caps can bend or discolor from the heat rising through them. On a factory-built fireplace, the listed metal chimney can be damaged in ways that call for replacing sections with the maker's parts.

Quiet chimney fire signs you might have missed

The signs of a chimney fire that burned quietly are easy to miss, because nobody was looking for them. Watch for any of these, especially if the fireplace was used heavily or hasn't been swept in a while.

• Puffy, honeycomb-like creosote clinging to the flue or piled behind the damper, very different from the flat, flaky kind.
• Burned, flaky bits of creosote scattered on the roof, in the gutters or on the lawn under the chimney.
• A damper that's bent out of shape or won't close the way it used to.
• A cap that's discolored, bent or heat-damaged.
• Cracked or collapsed flue tiles, or pieces of tile in the firebox.
• Cracks in the outside brick, or smoke seeping through the masonry during a later fire.
• Discolored or damaged roofing material near the chimney.

Why the fireplace stays dark until it's inspected

A flue that went through a chimney fire can look fine from the room and still be damaged inside. A cracked liner lets heat and smoke reach places they shouldn't, and the next ordinary fire can do what the chimney fire started.

A suspected fire can damage parts that are not visible from the room. Leave the fireplace unused while the condition and any need for further access are evaluated. A small fire or apparently clean opening is not a test of whether the chimney remains suitable.

The same goes if you only suspect a quiet fire. If the clues above sound familiar, treat the chimney as damaged until someone has looked.

Waiting costs very little. Using a damaged flue risks a second fire that finds the cracks the first one made, and that's the one that can reach the house.

How our pros check a flue the fire went through

After a suspected chimney fire, leave the fireplace unused until its condition has been assessed and necessary work completed. An initial inspection may not expose the whole liner or concealed construction. Further access or evaluation can be needed before deciding whether it is suitable to use.

The assessment may include accessible firebox, venting and exterior conditions. Suspected heat damage around concealed framing can require further investigation. The initial visit should not be described as measuring clearances inside every wall.

Ask which damage has been observed, what remains uncertain and what further access or specialist work may be needed. A written repair estimate should reflect the established scope rather than imply that every concealed area has been cleared.

What the repair can involve

The outcome can range from cleaning and further assessment to repair or replacement of damaged components. Visible damage alone does not establish the full scope. The decision must account for the appliance, venting and any hidden areas that still need investigation.

Others need more. Cracked clay tiles can mean relining the flue with a listed liner. A damaged smoke chamber may need rebuilding or parging. Cracked brick outside may need repointing or replacement. Heat damage to framing near the chimney is carpentry, and your quote will say who handles it.

The sequence of cleaning, investigation and repair depends on the condition found and safe access. Before returning to use, confirm that the required work and assessment are complete. A visible surface check cannot alone establish the condition of the whole route.

Starving the next fire of fuel

Correct operation with approved dry fuel and regular professional maintenance helps reduce chimney-fire risk. A recently swept chimney is not a guarantee against fire, and maintenance cannot compensate for damage, an incorrect installation or misuse.

Follow the maintenance interval for the appliance and chimney and arrange additional attention when deposits or symptoms warrant it. Cleaning reduces accumulated fuel, but no sweep guarantees that a chimney cannot burn or that other fire hazards have been eliminated.

When the firefighters have gone

After emergency responders have addressed the immediate fire, arrange an assessment before further fireplace use. Our local team offers a free inspection and written repair estimates, including any additional access or evaluation needed. Your first service receives 10% off. Discuss chimney inspection at (352) 675-6366.