The essential guide to cottage chimney maintenance

Photo by Erin Leydon

The essential guide to cottage chimney maintenance is one of our three-part series about chimney maintenance, along with:
Chimney 101: get to know your smokestack
Worried about creosote? Here’s what to look for

The stone hearth at Tom Clark’s Bruce Beach, Ont., cottage has presided over four generations of family history—raucous card games, fishing tales, even the anxious war years before Tom’s time, when his father was overseas. “Those were the only summers at the cottage my father ever missed,” says Tom, a Texan whose own northern pilgrimage has also been disrupted, this time by COVID. 

But the sands of time—or to be more exact, the chimney’s shifting foundation—haven’t been kind to the structure that Tom’s great-grandfather built in 1922.

Photo by Erin Leydon

Now it’s Bruce Beach’s own Leaning Tower.“It has moved seven inches in my lifetime,” Tom says. Not only that but the chimney is leaning on the cottage frame, so “the floor is stressed, the door is stressed, the ceiling, the roof, they’re all stressed.” Tom is stressed too. “We don’t want to reach the level of risk where it could fall on someone.”

That’s the thing about chimneys—they’re the quiet types that you never expect to act out. “People think of the chimney as a simple exhaust system, but it’s more than that,” says John Gulland, one of the originators of Canada’s Wood Energy Technical Training (WETT). Chimneys are among the hardest-working structures in the cottage—“the engine that drives the wood-heating system,” as Gulland puts it. 

Chimneys whisk smoke up and away, shield the cottage from toxic combustion gases and dangerous heat, and supply the all-important draft for efficient burning. But they’re also exposed to extreme temperatures, corrosive condensation, stormy weather, and red squirrels. Before your chimney blows its top or keels over, plan an intervention. Show it some love. 

Get to know your inner chimney

With a roar like a jet engine, fire shooting out over the roof, and combustion so intense that stovepipes glow red and shake, the classic cottage chimney fire “is incredibly scary when it happens,” says Jon Pegg, the fire marshal for the province of Ontario. And it happens often enough: almost 19 per cent of Ontario cottage fires between 2015 and 2019 involved woodstoves, fireplaces, chimneys, and a statistical category including hot ashes, embers, and sparks. 

While smoke and carbon monoxide alarms and a cottage fire escape plan are must-haves, so is checking your chimney for creosote, the tarry remnant of incomplete combustion that fuels chimney fires, and soot, the flammable residue of unburned carbon (see “Worried about creosote? Here’s what to look for”). Because creosote bungs up a flue the way cholesterol clogs arteries, the fire code mandates an annual chimney checkup—“whoo-hoo,” you’re probably saying, “another seasonal rite of cottaging”—as well as after a chimney fire, and when a new woodstove, fireplace, or fireplace insert is installed. 

Dryden Fire Service fire prevention officer Jadie Scaman says the fire code doesn’t specify who must do the inspection. Some insurers require occasional WETT inspections, but in practice many “annual inspections” are probably conducted by cottagers when they clean their chimneys. Nevertheless, it’s a good idea to have a WETT-trained inspector or chimney sweep in to check the system. “These are technical issues, so hiring a WETT-certified technician is the best bet,” Scaman says. 

To keep your insurer happy (and meet the fire code) you should also hold onto inspection reports for two years. At the very least, if you’re checking your own chimney, snap a dated photo of the interior of the flue (the metal pipe or clay liner that conveys smoke up the chimney).

On top of all that, clean your flue whenever there’s more than three millimetres of soot or creosote—the thickness of just three or four stacked dimes. How are you going to know when you’ve got 40 cents of creosote? You’ve got to look. 

If you can safely get on the roof, unscrew the chimney cap and peek Santa-style from the top with a flashlight, eyeing the edge of the flue pipe or liner to gauge the thickness of the creosote. Creosote deposits tend to be thicker near the top of the chimney, where suspended tar is more likely to cool and condense, so the advantage of looking from the top is that you’re seeing what’s likely the worst part of the system. If you’ve got a straight shot sightline in your chimney, from ground level you can look up through a conventional fireplace through the cleanout on a masonry chimney, or by removing stovepipes, or opening the inspection port on a metal chimney. You may also be able to look up through the appliance itself when the upper baffle is removed (check your manual or consult with your stove retailer—not all units permit this). Lower reaches tend to be hotter and cleaner, so if you have creosote plastered inside your stovepipe, you’ve probably got a bigger problem higher up. 

Monitoring creosote is especially important for wood-burning newbies, or cottagers who’ve bought a new stove and are learning how to operate it. Creosote is your wood-burning “report card”: too much, and you’re doing something wrong with the stove, or burning wet wood. Once you get the hang of it, and if you’ve got a good installation and an efficient stove, an annual cleaning should be sufficient. 

Worried about creosote? Here’s what to look for

Use a flashlight and mirror to see around corners, or go high-tech: “I use my iPhone and take a shot right up the chimney for my customer,” says Sean Mason, a second-generation chimney sweep and the owner of Brent Mason Chimney Cleaning in Sudbury, Ont.

Chimney detox

A thorough scrub from a WETT-certified chimney sweep ranges from about $150 to $350, but the safety, maintenance, and operating insights that come along with an experienced sweep’s inspection could be priceless. Even cottagers who do their own sweeping should call a pro every few years “just to be sure that no flaws have been overlooked,” John Gulland says.

No surprise, then, that when fire marshal Pegg bought his Georgian Bay cottage, “one of my very first calls was to have the chimney inspected and cleaned…I want the peace of mind that my system is safe.” 

Cottagers who do their own chimney cleaning (ideally as a supplement to professional cleanings and inspections) should use gloves, safety glasses or goggles, and a dust mask to reduce soot exposure, and use a chimney brush in an up-and-down scrubbing motion on straight sections. Carefully remove stovepipe elbows and carry them outside for cleaning, because standard fibreglass rods will not negotiate a 45 or 90-degree bend. (Carry pipes out in a bucket to contain the mess.) Be sure to use polypropylene (plastic) bristles on stainless steel flues. “Metal never touches metal,” cautions Yvette Aube, the chief administrative officer or self-described “chimney chick” at AIM Chimney Sweep and Stove Shop in Midland, Ont. “All that does is score the interior and give the creosote a place to adhere to.” Check for buildup in the fall so you can address any repairs that need to be made before winter, and aim for annual cleaning in the spring, so creosote sitting in the system doesn’t cause corrosion during humid summers. And remember, use a brush that’s the same size and shape as your chimney—square brushes in square chimneys, round in round. Sweeps get hired to fix all kinds of DIY errors, including stuck brushes and rods. 

Finally, chimney cleaning logs and soot-removing chemicals won’t do the job alone, and may cause flammable particles of creosote to fall off the liner and collect in the system’s horizontal surfaces. Only use chemicals “if you’re guided and schooled by a chimney professional,” says Aube, and as a stop-gap before a professional sweep. 

Chimney 101: get to know your smokestack

Seek liner wholeness

Fragile clay liners are “the most vulnerable part of masonry chimneys,” John Gulland says. Whether the flue is metal or clay, eye it for gaps, cracks, or holes after cleaning. (The classic hack is lowering an automotive trouble light—a bulb in a protective cage on a long cord—but a powerful battery-powered LED lantern would work too.) Cracks caused by high heat can allow a flammable mix of creosote and water to seep into the bricks and mortar, leaving telltale dark stains.

Replace liners that are broken, cracked or—eek—completely missing with rigid or flexible stainless steel. (Some people choose to add ceramic fibre insulation as well.) It’s a fiddly job, so budget roughly $2,000 or more for professional installation.

Put a lid on it

“Stone and brick chimneys need regular maintenance, most frequently from the top,” Gulland says. Whether metal or masonry, well-dressed chimneys require a cap to prevent water from mixing with creosote to form a corrosive slurry. Masonry units need an additional cap (also known as a crown), to seal moisture out of the top of the structure and deflect rain away from brick and stonework. A flexible bead of silicone in the “bond break” between the cap and clay liner allows the clay to expand and contract without letting rain in.

The only way to check the crown is to climb up there and have a close look. Because damage is invisible from the ground, “nobody notices the problem until there are bricks lying on the grass and the deck,” Sean Mason says. “We rebuild four or five chimneys a summer. For ninety bricks and a metal cap, you’re looking at around $2,000.”

Find balance 

Are you seeing widening gaps between chimney and flashing, roofing, and siding? That’s bad news: your hulking five or six-tonne fireplace could be shifting. “It’s a warning sign,” says  Kim Pressnail , a professor emeritus in civil and mineral engineering at the University of Toronto. “You need to find the root cause and solve the problem. You’re dealing with a structure that could kill someone.”

For minor leans, one option is a partial demolition: hire a contractor to lop off the masonry above the roofline (as in photo above), reducing the chimney’s heft so it’s no longer teetering towards destruction. With the base stabilized, a WETT pro can install a fireplace insert and factory-built metal chimney atop the remaining masonry. You’ll likely pay at least $6,000, not including the partial chimney demolition and any additional repairs that the cottage needs from the strain caused by the lean. Aube says a rebuilt or partially rebuilt chimney will run you into the thousands of dollars.

As for shoring up the chimney, options include jacking up and stabilizing the structure, excavating under it and pouring an expanded foundation, or underpinning it with helical piles—metal, augur-like sections that corkscrew into stable soil. These are complex approaches, likely to run well into five figures. You’ll also need to find an experienced mason and an engineer with a good grasp of foundations, structures, and the load-bearing capacity of local soils. 

In other words, it can be done. But should it be? Given the time, money, and construction safety challenges involved in righting a chimney with a bad lean, Pressnail says outright demolition and replacement is likely the simpler and cheaper option. “I feel for people who have chimneys with sentimental value,” he adds. “But if you can’t afford to fix the chimney properly I think the best practice is to take it down.”

Back at Bruce Beach, the Clark family is grieving their fireplace’s slow decline. “For 15 years, I think we’ve been thoroughly analyzing all the possible options. We’ve been trying to make a decision as a family,” Tom says. The verdict? Three or four years from now, the Clarks will likely gather around a natural gas fireplace. It’s safe, convenient, and much cheaper than restoring the old hearth as if it was a museum piece. But it’s still sad. “It hasn’t been an easy decision,” Tom says. 

As for the rounded, glacial stones his great-grandfather assembled in 1922, Tom’s been joking for years that they want to return to the beach. Soon they will. “I want to use them in a decorative, memorial kind of way,” Tom says—maybe as a garden wall, or a bench with a good view of Lake Huron sunsets. Though their time near the fire is ending, the rounded granite, quartz, and gneiss of the old hearth will continue on as links to—and witnesses of—a new century of Clark cottage history.

This article was originally published as “Up in Smoke” in the Fall 2021 issue of Cottage Life.

Worried about creosote? Here’s what to look for

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