Base & Apron Flashing
Installed along the downhill face of the chimney, the metal apron sits over the lower roof shingles and directs water running down the chimney face out onto the roof surface.
Where your brick chimney passes through the roof deck is one of the most vulnerable water-entry points on any home. If you notice damp drywall near your fireplace, stained attic rafters, or lifted metal around the chimney base, request a chimney flashing repair Ottawa quote below to connect with an independent local service provider.
Share your contact information, your Ottawa-area location, and what signs of moisture or flashing wear you have noticed so an independent local contractor can review your inquiry.
A timber-framed roof and a heavy brick chimney expand, contract, and settle at different rates through every Ottawa season. Because rigid caulk or mortar alone will quickly crack at that intersection, proper chimney flashing uses a two-part overlapping metal system that sheds water while allowing both structures to move independently:
Installed along the downhill face of the chimney, the metal apron sits over the lower roof shingles and directs water running down the chimney face out onto the roof surface.
L-shaped metal pieces woven course-by-course between each layer of roof shingles up the sides of the chimney, channeling rainwater downward from shingle to shingle.
Set directly into horizontal mortar joints (reglets) cut into the brickwork and folded down over the top edge of the step flashing so water running down the brick cannot slip behind the metal.
On wider chimneys, a peaked ridge ("cricket" or saddle) is built on the uphill roof slope behind the stack to split sliding snow, ice, and heavy rainwater around the chimney base.
Homeowners searching for leaking chimney flashing assistance often discover the problem indoors first after a heavy rainstorm or mid-winter thaw. Common indicators include:
Even heavy-gauge metal flashing does not last forever. Across Ottawa neighbourhoods, flashing leaks usually trace back to one of three underlying issues:
When roof shingles are replaced, contractors sometimes reuse old, nail-riddled step flashing or surface-caulk metal flat against the brick face instead of cutting proper counter-flashing into the mortar joints.
If the mortar holding the upper counter-flashing crumbles from freeze-thaw weathering—or if the roof framing and masonry settle slightly—the metal lip pulls out of the brick joint and opens a gap for rainwater.
Older galvanized steel flashing eventually rusts when exposed to decades of wet leaves, acidic soot runoff, and heavy ice dams pushing underneath the metal seams along the uphill side of the chimney.
Depending on the age and condition of the existing metal and surrounding shingles, an independent contractor may discuss either a localized repair or full chimney flashing replacement Ottawa:
If the underlying step flashing and shingles are relatively new and properly interwoven, a localized repair may address the issue without tearing up the surrounding roof.
When flashing was installed improperly, buried under layers of cracked roofing tar, or rusted through, patching over the surface rarely holds up through an Ottawa winter.
Not every water stain near a fireplace is caused by faulty flashing—and replacing the flashing alone is not guaranteed to stop every chimney leak. Water entering a chimney high above the roofline often travels downward inside the brick cavity before showing up at the ceiling line right next to the flashing.
Before recommending chimney roof leak repair Ottawa, an experienced contractor checks multiple potential moisture sources so you don’t pay to fix the wrong component:
While each independent contractor follows their own diagnostic and installation practices, addressing a suspected flashing issue generally follows three steps:
The contractor inspects the base apron, step flashing, counter-flashing reglets, adjacent shingles, and the upper brick and crown to trace where water is actually entering.
You receive an explanation of the findings—whether the metal flashing needs re-bedding, full replacement, or accompanying mortar repair—along with the provider’s estimate.
Old tar or damaged metal is removed, step and counter-flashing are properly fitted into the shingles and mortar joints, and any adjacent brickwork gaps are sealed.
In the Ottawa region, heavy wet snow piles up against the uphill side of roof chimneys throughout January, February, and March. As heat escaping from the attic or warm chimney flue melts the bottom layer of snow, water pools behind the chimney base and refreezes into thick ice dams. If the uphill saddle flashing or step flashing has any open seams, standing meltwater is forced backward under the shingles and into the roof deck.
Having suspect flashing inspected and repaired during spring, summer, or autumn—before snow and ice cover the roof—makes rooftop work safer and helps prevent mid-winter chimney water leak repair emergencies.
Whether you own a steep-roofed heritage home in central Ottawa, a bungalow in Nepean, or a two-storey home in Kanata, Barrhaven, Orleans, or Stittsville, keeping the chimney-to-roof transition watertight protects both your roof framing and interior finishes.
Homeowners across these communities can submit a request on Ottawa Chimney Pros to connect with an independent local service provider, subject to contractor availability and coverage.
Answers to key questions about chimney roof leaks, flashing inspections, cost factors, and lasting repair methods.
Not always. While damaged or improperly installed flashing is a very common cause of leaks around the chimney breast, water can also enter through a cracked concrete chimney crown, an uncapped flue, eroded mortar joints higher on the stack, or worn roof shingles uphill from the chimney. An on-site inspection is essential to pinpoint the actual entry point—or combination of entry points—before deciding on a repair.
Smearing black roofing cement over a flashing leak is a short-term patch at best. Because your wooden roof deck and brick chimney expand and shift independently in Ottawa’s heat and winter frost, rigid tar quickly splits open—and can even trap water behind the metal. Lasting flashing work relies on overlapping step flashing and counter-flashing anchored into the mortar joints.
Independent contractors base their quotes on whether the flashing requires a minor re-anchoring and mortar seal or a complete tear-out and replacement of step and counter-flashing, as well as the width of the chimney, roof pitch and height, shingle condition around the base, and whether a cricket diverter or brick repointing is also needed.
Installing new step flashing and checking the masonry counter-flashing during a shingle replacement is generally recommended, since old flashing often has nail holes or corrosion that will fail long before the new shingles wear out. If your roof was recently replaced and a leak appeared afterward, a chimney or roofing specialist can inspect whether the step and counter-flashing were properly integrated.
Ottawa Chimney Pros is a referral website that connects homeowners with independent local chimney and masonry service providers. When you submit a request using the quote form on this page, your inquiry details may be shared with an independent contractor serving your area so they can contact you to discuss an inspection and estimate.
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