Creosote buildup in a fireplace: asking the seller

What should you do about creosote buildup in the chimney?

If your inspection report flags creosote, a stuck damper or a missing cap, book a certified chimney sweep for a Level II inspection before your deadline. Creosote is the residue wood smoke leaves inside the chimney. The Chimney Safety Institute of America (CSIA) calls it "highly combustible." Have the sweep price the cleaning, cap and damper on one bid, then ask the seller to pay for it or credit you the total.

NFPA 211, the National Fire Protection Association's chimney standard, sets three levels of chimney inspection. CSIA's Level 2 procedure recommends a Level II "when the property is being sold." The sweep goes on the roof, checks the attic, basement and crawl space, and video scans the chimney's interior.

Key takeaways

• Inspectors following International Association of Certified Home Inspectors (InterNACHI) standards don't have to look inside the chimney. Negotiate from the sweep's report.
• CSIA says to sweep a masonry fireplace at 1/8 inch of sooty buildup, and sooner if any glaze is present.
• A Level II with cleaning, a galvanized steel cap and a damper repair run $725 to $1,710 at national prices.

What does it cost to fix?

Compare each cost row with the fix on your report, since prices differ mostly by scope. The sweep's written bid replaces all of them.

Here's one full scope at those national prices: a Level II with cleaning, a galvanized steel cap installed, and a damper repair. Level II with cleaning, Bob Vila wood-burning sweep range: $300 to $1,000. Low ends: $300 + $325 + $100 = $725. High ends: $1,000 + $485 + $225 = $1,710. Glazed creosote that needs a chemical treatment is not in that total, so it goes on the sweep's written bid.

Kept prices every line of an inspection report for $79, usually under 4 hours, and marks the ones that need a professional quote. For how fast a sweep can get you a figure, see how to get repair estimates during the inspection period.

Is creosote buildup dangerous?

Yes, creosote buildup can start a chimney fire. CSIA says that happens when it builds up enough and the flue runs hot enough. Creosote is black or brown, and can be crusty and flaky, tar-like and sticky, or shiny and hardened. A fireplace that smells in summer is another clue, since that odor comes from creosote deposits in the chimney. Fire safety experts, per CSIA, treat 1/8 inch as "enough buildup to cause a chimney fire capable of damaging the chimney or spreading to the home."

Past fires are the other worry. CSIA says "the majority of chimney fires go undetected," yet they can still damage the chimney. A sweep looks for the signs CSIA lists, such as "puffy" creosote, a warped damper and a distorted rain cap. The home inspector's report won't settle it. An inspector need not "inspect the interior of chimneys or flues" or "determine the need for a chimney sweep," under InterNACHI's Standards of Practice. Don't light a fire in it until a sweep has seen it.

What if the damper is stuck or missing?

The damper is the metal plate that seals the fireplace when it isn't in use. InterNACHI inspectors open and close it if it's accessible and hand-operated, and report one that doesn't open and close. A damper that doesn't work, or one left shut during a fire, can mean "a smoky room at best and a fire hazard at worst," per CSIA's homeowner guide.

A chimney company, Chimney Specialists, lists the usual failures: a damper that comes off its track, stops working, or is cracked or missing.

Ask the sweep whether a damper can be added if there's none, and put it on the bid. Whether your town requires one is a question for the local building department.

Do you need a chimney cap?

Yes, says cap maker HY-C. A cap keeps out rain, sleet and snow. It also keeps out animals such as raccoons and birds. And it can prevent downdrafts that push smoke back into the house. HY-C adds that "weather and wildlife can still get in, even if you never use your fireplace."

A missing "flue cap" gets the same fix. HY-C describes caps as "installed on top of your chimney flue or crown." Ask the sweep whether water or animals already got in. Any damage goes on the same bid.

What should you ask the seller for?

Ask for each line on the sweep's written bid, by name and price. If the seller hires the sweep, ask for the sweep's inspection report and invoice before closing. If you'd rather hire your own, ask for a credit equal to the bid. What to ask for after a home inspection shows how this line fits the rest of your list. The buyer repair request letter template gives the wording around it.

If the seller says no, check whether your inspection contingency lets you cancel inside the window. Your contract sets the exact dates and terms, so confirm them with your agent. Compare the refusal with the sweep's figure, and see when to walk away after a home inspection for how to weigh it.

What dissolves creosote in a chimney?

For gummy creosote in a chimney, CSIA says a chemical treatment or an acid application is "about the only way to deal with the creosote." Acid must be neutralized a few days later. For crusty creosote, CSIA says rotary cleaning can help. Chemical cleaners "would never be considered adequate on their own," so plan on a professional sweep either way.

What if the report also flags a wood stove?

A stove set too close to a wall or floor is a separate finding with its own fix. See wood stove clearance to combustibles on an inspection report.

How do I price the rest of my report?

Price the rest of your report line by line before you send the request, so the chimney bid sits inside one total.

If the chimney is one line of many, upload your inspection report to Kept. Your time then goes to the lines that need a sweep's bid.

Sources

• Chimney Safety Institute of America, "Preventing Chimney Fires"
• Chimney Safety Institute of America, Homeowner Resources
• Chimney Safety Institute of America, Level 2 Inspection of a Masonry Fireplace
• InterNACHI, Home Inspection Standards of Practice
• HY-C, "Everything You Need to Know about Chimney Caps"
• Chimney Specialists, "The Damper Dilemma"
• Bob Vila, "How Much Does a Chimney Sweep Cost?"
• Bob Vila, "How Much Does a Chimney Cap Cost to Install?"
• HomeAdvisor, "How Much Does Chimney Repair Cost?"