Does my chimney need extra care after a heavy Ottawa ice storm where ice dams formed at the roofline around the flashing?

Yes, your chimney absolutely needs a thorough inspection after an ice dam event — and the sooner the better, because the damage from ice dam pressure and meltwater infiltration can progress quickly once freeze-thaw cycling resumes. Ice dams at the roofline create a reservoir of standing water that has nowhere to go except sideways and downward, and the chimney flashing is one of the most vulnerable entry points in the entire system.

What Ice Dams Actually Do to Your Chimney

Chimney flashing — the metal (typically aluminum or lead-coated steel) that seals the joint between the chimney and the roof surface — is already one of the most failure-prone components on any Ottawa home. It expands and contracts with temperature swings, the caulking and counter-flashing seals degrade over time, and even a small gap allows water infiltration. When an ice dam backs up against the chimney base, it forces water under the flashing under hydrostatic pressure rather than simple gravity. That water then finds its way into the chimney chase, the mortar joints at the base of the chimney, and potentially into the ceiling and wall cavities of the room below. In Ottawa's climate, that infiltration water then freezes, expands roughly 9 percent, and widens the gap further — so what started as a hairline crack in the flashing seal can become a serious opening after one bad ice storm.

Beyond the flashing, check the chimney crown — the concrete cap at the very top of the chimney. Ice dams don't typically reach the crown directly, but the freeze-thaw stress during and after an ice storm event is severe across the entire chimney structure. If the crown had any pre-existing hairline cracks, this winter may have turned them into visible fractures. A cracked crown allows meltwater to pour directly into the flue, which accelerates liner deterioration and can cause interior water damage.

Practically speaking, here is what you should do. First, once it is safe to access the area, visually inspect the flashing from the ground using binoculars — look for lifted, buckled, or separated metal, and check whether the counter-flashing (the piece embedded in the mortar joint) has pulled away from the chimney face. Second, go into your attic and look for water staining or active moisture on the ceiling decking around the chimney penetration. Third, check the firebox interior for water staining, rust, or debris that may have washed down the flue. Finally, and most importantly, have a WETT-certified chimney technician do a proper inspection before you use the fireplace again — they can assess flashing integrity, crown condition, and whether any water has compromised the liner.

Flashing repair in Ottawa typically runs $400 to $900 depending on how much of the flashing needs to be replaced versus re-sealed. A new chimney crown, if the existing one has cracked through, runs $300 to $1,200. These are not expensive repairs relative to the water damage that follows if you ignore them — a chimney that leaks through the winter can damage framing, drywall, and insulation in ways that cost far more to remediate.

Don't wait until spring to have this looked at. If you are actively using your fireplace through the winter, you want to know now whether the flue is compromised. You can browse chimney inspection professionals through the Ottawa Construction Network directory at justynrookcontracting.com/directory to find someone who can assess the full extent of the ice storm's impact on your chimney system.