What does it mean when black tar is dripping out of my damper?
Black tar dripping from the damper is liquid creosote, a flammable residue left by wood smoke that has built up in the flue and turned runny. Stop using the fireplace until a chimney technician has swept and inspected it.
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The tar is not the whole story. It means there is a lot more creosote above the damper, and moisture is often what is making it move. The sweep's job is to find out how much is there and why it is liquefying.
Why creosote turns to tar and drips
Smoke that cools before it leaves the chimney leaves deposits on the flue walls. Slow, smoldering fires, damp or unseasoned wood, and a flue that stays cold all make this worse. Layer by layer, the deposit goes from light soot to thick, tarry buildup. If a chimney has burned wood for a long time without being cleaned, that buildup can be heavy.
Creosote softens and runs when moisture reaches it. That moisture can come from condensation inside the flue, or from water entering through a failing cap, crown or flashing. The tar then works down the flue and collects on the damper and smoke shelf, and sometimes drips into the firebox.
Creosote is fuel. A flue coated in it, sitting inside the house, can feed a chimney fire. If you ever hear a roaring from the chimney or see flames at the top, get everyone out and call 911.
What you can check yourself
Look, don't touch
Use a flashlight to see where the tar is. Avoid touching or wiping it. It stains badly and spreads easily. Don't scrape it or try to clean it out.
Smell the room
A sharp, acrid, smoky or tar-like smell, especially when the weather is damp, points to heavy creosote. Note when the smell is strongest so you can tell the technician.
Check the damper handle
See whether the handle moves freely or feels stiff and sticky. Don't force it. Tar on the damper plate can make it hard to open or close fully.
Look at the firebox walls
Shiny, flaky or crusty black deposits on the firebox or smoke shelf area tell the technician how much has built up. Take a photo to show them.
Test your alarms
Press the test button on your smoke and carbon monoxide alarms. If anyone has a headache or dizziness while a fire is burning, or an alarm sounds, go outside and call 911.
When to call a technician
Tar at the damper is already past the point of looking and listening. Don't burn anything until the flue has been inspected, even if the drip seems minor. The amount you can see is only a small part of what is likely above it.
One Call Chimney is a referral and scheduling service. One call to (866) 576-7943 arranges a visit from an independent sweep or mason. The estimate is free, the technician inspects the chimney and gives the price before any work starts, and you approve it first. If the inspection finds a liner repair or a crown or cap problem, ask your local building department whether that work needs a permit where you live.
What the technician will do
- Sweep the flue top to bottomThe technician removes the creosote and debris. Heavy or glazed tar deposits may take more than a standard sweep, and the technician can explain what yours needs.
- Camera-inspect the whole flueA camera shows what the sweep can't see from below. Ask to see the footage so you can see the buildup and any damage for yourself.
- Check the linerThe liner is checked for cracks and gaps. Damage there can let heat and smoke reach the walls around the flue.
- Clean the damper, smoke shelf and fireboxThe tar is cleared from the damper and the smoke shelf above it, and the firebox is cleaned out.
- Inspect the cap and crownIf water is getting in and softening the creosote, the cap and crown are usually where it enters. Ask for the findings in writing.
Related questions
- Is black tar in the damper a sign of a chimney fire?
- Not by itself. It does mean there is plenty of fuel in the flue, which is what a chimney fire needs. A roaring sound or flames at the top of the chimney is a chimney fire: get everyone out and call 911.
- Can I just wipe it up and keep using the fireplace?
- Wiping removes only what has dripped down. The deposit above is still there, and it can still ignite. Hold off on fires until a technician has swept and inspected the flue.
- Will a sweep find out why the creosote is liquid?
- Yes, that is part of the inspection. The camera can show whether the cause is condensation inside the flue or water coming in at the cap or crown. The technician can then explain the repair in writing.
- How do I avoid it coming back?
- Burn well-seasoned wood, give the fire enough air so it burns hot instead of smoldering, and have the chimney swept and inspected regularly. If water is getting in, fixing that source matters as much as the sweep.
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