What a cleaning takes out

Creosote, soot and whatever has fallen or crawled into the flue. Nests, leaves, chunks of broken tile.

Creosote is the main event. It is the tarry residue wood smoke leaves behind as it cools on the way up. Thin and flaky at first. Left alone it builds into a hard glaze that grips the flue wall like enamel.

Soot is the loose black powder underneath it. That comes off easy. We brush it down and the HEPA vacuum catches it before it drifts.

Then there are the blockages. Birds nest in open flues every spring. Leaves pack in over autumn. Bits of cracked tile drop and wedge in the smoke shelf. Any of it chokes the draft and pushes smoke back into the room.

A clean flue draws properly. That is the whole point. Smoke goes up and out the way the chimney was built to send it.

Why creosote is the one that matters

Creosote is fuel, and enough of it in a hot flue is how a chimney fire starts.

A chimney fire is not a metaphor. The glaze on the flue wall ignites, the temperature spikes past a thousand degrees, and the sound people describe is a low roar like a jet. Clay tile cracks under that heat. Sometimes the fire finds its way into the framing behind the brick.

The fix is boring and it works. Take the creosote out before it builds up. NFPA 211 puts the trigger at one eighth of an inch of buildup, and once a flue reaches that it needs sweeping before the next fire.

Burn habits change the pace. Wet or unseasoned wood glazes a flue fast. A slow smoldering fire coats it faster than a hot clean one. If you load the firebox and damp it down overnight, you are making creosote all night.

How we clean a chimney

1. Cover the room

   Drop cloths over the hearth and the floor in front of it, and the firebox opening sealed so nothing escapes into the house.

2. Set up the vacuum

   A HEPA vacuum runs the whole time and holds the flue under slight suction. That is what keeps the soot out of your living room.

3. Brush the flue

   Wire or poly brushes on rods scrub the full length of the flue. Top down or bottom up depending on the roof and the setup, and the creosote comes down as we go.

4. Clear the firebox and smoke shelf

   The debris that falls collects on the smoke shelf behind the damper. We clean that out along with the firebox and the damper itself.

5. Level I inspection

   With the flue clean we run a Level I check of what is readily visible. If something needs a closer look you hear about it before we leave.

Want the camera up the full flue as well? That is a Level II inspection.

How often it needs doing

Once a year for an inspection, and a cleaning whenever creosote reaches an eighth of an inch. For most wood burners that lands around a cord.

NFPA 211 asks for an annual check whether or not the flue looks dirty. The cleaning itself depends on how much you burn. A household that goes through a cord or two a winter usually needs a sweep every year. A fireplace lit twice at Christmas can go longer.

Gas changes the math. Gas logs leave far less residue, so the flue stays cleaner, but the venting still fouls and the system still needs an annual look for blockage and corrosion.

People use cleaning and sweep to mean the same job, and they are close. We treat a cleaning as the full sweep plus the Level I inspection that comes with it.