How to Clean a Chimney

Cleaning tips for a wood-burning fireplace chimney.

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Introduction

Regular cleaning with a shop vac and standard chimney cleaning tools will prevent dangerous creosote fires. Here's what you need to know before you get started.

Tools Required

  1. Drop cloth
  2. Dust mask
  3. Flashlight
  4. Flue liner brush
  5. Long-handled brush
  6. Noodle brush
  7. Safety glasses
  8. Safety harness
  9. Shop vacuum

Materials Required

  1. Duct tape
  2. Poly sheeting

Intro to chimney maintenance: Meet the pros

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Jim Smart has owned Smart Sweep Chimney Service for 14 years. He and his son Jesse are certified professional chimney sweeps. Together, this father/son team inspect, clean and repair chimneys in the Minneapolis/St. Paul area. Jim also holds a certificate in forensic chimney fire analysis. If you use your fireplace or woodstove regularly but can’t remember the last time your chimney was cleaned, it’s probably overdue. In many cases, you can clean the chimney yourself and save a few hundred dollars.

Removing ordinary chimney soot is pretty simple. But if you have heavy creosote buildup, you’ll have to call in a pro. We’ll show you how to inspect yours to see if it qualifies as a DIY job. If it does, just follow these steps. Otherwise, hire a certified chimney sweep.

Is fireplace cleaning a DIY job?

Figure A: Chimney cutaway

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Clean creosote buildup from all parts of the chimney. Most chimney fires start in the smoke chamber/smoke shelf area, so it’s the most important area to clean (Figure A). Since that area is hard to reach in some fireplaces, check yours to see if you can reach into it and still have room to maneuver a brush. If you can’t reach it, this isn’t a DIY project.

Next, see if you can access the chimney crown. If you have a very steep roof pitch or aren’t comfortable working on your roof, then this isn’t a job for you. Call a certified chimney sweep. If you decide you can handle the heights, make sure to wear a safety harness.

Chimney Fires Destroy Homes

Creosote buildup may not look dangerous, but it ignites at a mere 451 degrees F, and once it starts burning, it expands like foam sealant. In less than a minute, it builds to more than 2,000 degrees F and can engulf your entire chimney and destroy your home.

Even if you clean your chimney regularly, you should still have it inspected by a qualified chimney sweep once a year. Certified chimney sweeps are trained to recognize chimney deterioration and venting problems and can assess your chimney’s condition.

If you burn mostly green (wet) logs, have your chimney cleaned or inspected every 50 burns. If you see moisture bubbling out the ends of the logs when they’re burning, the wood is wet. This green wood doesn’t burn cleanly and sends a lot of unburned particles (smoke) up the chimney, where they build up as creosote and soot. Dry hardwoods, such as oak and birch, burn hotter and cleaner. With them, have your chimney cleaned or inspected every 70 burns.

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A quick way to tell if your chimney needs cleaning is to run the point of your fireplace poker along the inside of your chimney liner. If you find a 1/8-in. or more layer of buildup (the thickness of a nickel), call a chimney sweep. Chimney sweeps may see 40 to 50 chimney fires a year, and more than half of the chimneys they service require extra cleaning because the homeowners wait too long before calling. In extreme cases, the hardened layer of buildup requires cleaning with special tools or chemicals.

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A professional cleaning includes an inspection for soot buildup, obstructions, cracks in the chimney liner and signs of water damage. Older chimneys often have gaps between clay liner sections where the mortar has fallen out.

When hiring a chimney sweep, look for someone who’s certified and insured and will provide an upfront cost estimate. (For a list of certified chimney sweeps, contact the Chimney Safety Institute of America at csia.org.)

Do an inspection

Strap on goggles and a respirator, clean the ashes out of the firebox and remove the grate. Then open a door or window and wait a few minutes before opening the damper so the pressures equalize. Then open the damper and wait a few more minutes for heat to rise from the house.

Grab your brightest flashlight and a fireplace poker and lean into the firebox. Shine your light into the smoke chamber and flue and use the poker to scratch the surface. If the soot has a matte black finish and the scratch is 1/8 in. deep or less, it’s a DIY job. But if the buildup is deeper or has a shiny, tarlike appearance, you have heavy creosote buildup. Stop using your fireplace immediately and call a professional chimney sweep.

Project step-by-step (5)

Step 1

Get the right cleaning tools: Match the brush to the flue liner

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Buy a metal bristle brush for a clay flue liner and a brush with plastic bristles for a metal liner. Buy enough rods to handle the entire height of your chimney.

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Step 2

Get special brushes for the firebox

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Buy a bendable “noodle brush” to clean the smoke shelf and a long-handled brush to clean soot off the sides of the firebox. There’s no “one-size-fits-all” brush for cleaning the flue. So you’ll have to climb up on your roof and measure the size of your flue liner. You’ll also need special brushes for the firebox and smoke chamber areas. Find the equipment at a home center or at an online store such as efireplacestore.com.

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Step 3

Minimize the mess: Protect your interior

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Lay a canvas tarp over the hearth and spread it into the room. Then tape poly sheeting over the fireplace and insert a shop vacuum hose. Seal everything with duct tape.

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Step 4

Vent to the outdoors

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Add sections to lengthen the vacuum hose, then connect it to your shop vacuum outside. Run the vacuum while you brush, and replace the filter when it clogs. Before you start brushing, protect your home's interior from soot with poly sheeting, a canvas tarp and a shop vacuum. Most shop vacuum filters can't trap all the fine soot from a fireplace, and some of it will blow right out the exhaust port. So buy extra lengths of vacuum hose and move the vacuum outside. Then close the doors and windows on that side of your house to prevent the soot from reentering your home.

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Step 5

The cleaning process: Brush the flue

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Ram the cleaning brush up and down several times in a small section of the flue to remove chimney soot. Use a bright flashlight to check your work before moving on to the next section. Start the vacuum and begin fireplace cleaning at the top of the chimney. Continue adding rods and moving down the chimney until you can’t feel any more brush resistance. That means you’ve reached the smoke chamber and it’s time to climb down from the roof and work from inside the firebox.

Peel back a small portion of the poly sheeting and use the long-handled brush to clean the smoke chamber. Use the noodle brush to remove all the soot from the smoke shelf. Then switch back to the long-handled brush to clean the sides of the firebox. Finish by vacuuming the entire firebox. Then fold up the poly sheeting and the canvas tarp and move them outside. Shake them out and reuse them the next time you clean the chimney.

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