It’s a dirty job. But if you don’t want to risk a chimney fire, someone’s got to do it.
For anyone over the age of 40, the phrase “chimney sweep” probably conjures up memories of Dick Van Dyke’s sooty face, derby cap and famously terrible Cockney accent in “Mary Poppins.”
Not so for the staff at Johnston’s Chimney Sweep, which has operated out of West Newton since the mid-1980s.
At a recent job in Charleroi, Matt Johnston and Harrison Vance were decked out in hard hats, harnesses and ventilators at various points as they installed a new chimney liner.
Between 2020 and 2024, there was an annual average of more than 12,200 chimney fires per year in the U.S., according to the National Fire Protection Association.
“Chimneys and vents should be cleaned and inspected by a qualified professional at least once a year,” said association spokesperson Susan McKelvey. “Only 6% of U.S. home heating fires involved fireplaces or chimneys, but they caused nearly one-fifth of the direct property damage.”
As a fire burns, some of the wood particles draft upward instead of falling down into the fireplace. In addition, the incomplete combustion of wood creates creosote, a toxic, oily, highly flammable byproduct that can stick to the inside of chimney walls and begin collecting those wood particles.
“As smoke rises, cools and condenses, it turns into creosote, which burns a good bit hotter than wood,” said Corey Flowers, owner at the Ohio Chimney Co. in Warren, Ohio. “And you want to make sure that’s not going to build up enough to take a spark.”
Johnston’s is a family-run business, started by Roy Johnston in 1984.
“I’d read about it, and when I checked to see if there were other businesses around the area, there weren’t too many at the time,” he said.
Today, a quick search for “chimney sweep” turns up 20 or so companies between Allegheny and Westmoreland counties, but it is still a relatively small industry, despite its necessity.
“I went into it part-time for about four years, then decided to go full time,” Johnston said.
“The need was there, and it enabled my wife to stay home with the kids.”
These days, Johnston’s wife, Doris, is part of the office staff, and his son Matt is part of the team.
“We have people certified for gas inspections, chimney inspections and dryer vents,” Matt Johnston said. “My dad is usually out in the field doing inspections and cleanings, and me and my crew are doing installations.”
As the business name implies, cleanings are the most common job.
“If you’re using your chimney on a regular basis, it’s recommended to clean it once a year,” Matt Johnston said. “When you don’t, that’s when you run into issues that could cause potential chimney fires.”
Matt Johnston said it only takes about a quarter-inch of soot and creosote to catch fire. Flowers said his company recommends cleanings at the even-lower threshold of an eighth-inch, about the thickness of a house key.
Chimney fire damage is largely caused by the massive thermodynamic shift that happens when the mixture of creosote and soot ignite.
“Your average fire is about 700 degrees, and your typical chimney exhaust is around 400 degrees,” Flowers said. “There’s a rapid change when creosote ignites, because it can burn at temperatures closer to 1,100 degrees. That thermal expansion is what causes a lot of damage.”
One of the true dangers of a chimney fire is that it can happen without a homeowner even realizing it.
“There are a lot of set-ups,” Flowers said. “With an open wood-burning fireplace, you’re more likely to hear a fast-burning chimney fire, especially if it’s sucking in air in to feed the flames. With a wood-burning stove, it’s closed at one end and so the intake and exhaust are the same hole, which makes it less likely to hear the fire and know there’s damage taking place.”
Flowers pointed to a white paper created by the Chimney Safety Institute of America, which asserted that the vast majority of homeowners who’ve had a chimney fire did not realize it at the time.
“That’s confirmed by what we’ve seen in the field,” he said. “We’ll do a first-time inspection and can immediately see evidence that there’s been a chimney fire. And the homeowner doesn’t know when it happened.”
Sometimes, buildup in a chimney isn’t the issue at all.
“Once we found a Teenage Mutant Ninja Turtles mylar birthday balloon stuck up in a chimney,” Roy Johnston said.
Other times, it might involve nonfiction creatures.
“Fireplaces have a damper and a shelf, and in the springtime, mother raccoons will go down in there to have a litter,” Matt Johnston said. “And even though the flue liners are pretty much smooth, they can still use their claws to get in and out.”
He said in those cases, they will call someone who specializes in animal removal, rather than trying to do the job themselves.
In warm weather, when people are not using their fireplaces, chimney sweeps like Johnston’s will often perform masonry and brick-pointing work.
“You see something different every day,” Matt Johnston said.
Both the Johnstons and Flowers emphasized the importance of letting a professional take a look at least once a year.
“Our understanding of thermodynamics has changed over the years,” Flowers said. “Fire doesn’t care what the building code was 50 years ago. Having that inspection done is really important to make sure a chimney meets — or even better, exceeds — current safety standards.”