Chimney sweeping expert James Mueller once found a duck inside a customer's chimney.

"Yes, a duck!" he exclaims, still obviously bemused at the situation. James says that while the homeowner did realize that some sort of animal had gotten into his chimney, he wasn't sure what it was. Needless to say, they were both surprised when James removed the damper assembly in the chimney and pulled out a duck, instead of the typical raccoon, squirrel, or backyard bird.

James and the homeowner set the duck down outside, in front of the home, and that was that, the end of one of the weirdest experiences he's had working in the chimney sweeping business.

His appointments are generally less exciting than that; most people call on James—a Chimney Safety Institute of America (CSIA)–certified technician from A-1 Safety Chimney Service—for routine maintenance. I asked him to tell me what you can expect if you hire a chimney sweep to come out to your house, besides someone to rescue confused animals, of course.

What happens during a typical chimney sweeping appointment?

Step 1: The technician and assistant lay a tarp in front of the fireplace and set up their equipment.

Step 2: The assistant sweeps the fireplace while the technician begins the inspection.

Step 3: The technician inspects the entire chimney system from bottom to top, getting on the roof to make sure everything is working properly.

Step 4: The technician snaps digital pictures and provides a written estimate for any repairs.

Step 5: The assistant sweeps the fireplace from bottom to top, a method that James says helps control the amount of soot that falls back down. They sweep the firebox, smoke chamber, and flue using rods and brushes, much like the most famous chimney sweep in the world, Dick Van Dyke. They finish by vacuuming off the smoke shelf.

How long is the average appointment?

Appointments typically take 60 minutes.

Why do you need to clean your chimney in the first place?

Cleanings get rid of the creosote that builds up in your fireplace. This black residue occurs when the oils in the wood don't burn off entirely and instead, accumulate inside your chimney. The more creosote buildup you have, the more you're at risk for a chimney fire because the residue is highly flammable.

There are three stages of creosote:

• Stage 1: a loose, flaky substance that resembles coffee grounds. It's the easiest to clean.
• Stage 2: a more advanced, tar-like substance that might require special brushes to remove
• Stage 3: a shiny, hard, black substance that's very difficult to remove. It may drip down from the chimney and into the fireplace when a fire reaches high temperatures.

Cleanings can also determine if there are any birds' nests or animals in the chimney, and if the chimney cap is still in good shape (the cap helps keep out said animals).

How often should you have your chimney checked?

According to the National Fire Protection Association Standard 211, chimneys, fireplaces, and vents should be inspected at least once a year.

What does a chimney sweeping cost?

The average cost for a fireplace sweep is $150, James says. However, he adds, it's not uncommon for the technician to discover problems that might cause the price to go up. "Common issues we run into are cracks in masonry, faulty or nonexistent caps/animal guards, rusted chase covers, unparged smoke chambers, cracked flue tiles, [and] third-stage creosote (also known as glazing)," James says.

What can you do to maintain your chimney between cleanings?

James, who personally has two fireplaces in his own home, recommends doing a "walk around," or visual inspection, twice a year to see if anything looks unusual. You can also:

• Clean ashes out from your fireplace; add the ashes to your compost pile to give it important nutrients.
• Refrain from burning anything other than dry firewood. Wet wood can cause more creosote buildup. So can materials other than wood, which is why you should refrain from tossing in things like pizza boxes and catalogs addressed to the woman who hasn't lived in the house in nine years.

Is there a special type of firewood you should use?

"As far as wood goes this is a common question I get asked. I tell people to avoid rotted or unseasoned [green] wood," James says. "Make sure you store your wood in a dry place, or make sure it is covered," he adds.

What's the worst thing someone with a chimney could do?

"Not maintaining your system is the worst thing you can do. When systems are not properly maintained, homeowners run the risk of setting their homes on fire, and at the very least, incurring costly repairs," James says. "It is a good idea to have your system inspected on a yearly basis, whether you use it or not."

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