How often should Ottawa homeowners have their chimney mortar joints inspected given our harsh winters and frequent ice storms?

Ottawa homeowners should have their chimney mortar joints inspected at least once per year, ideally in early spring (March to April) after the freeze-thaw cycle has done its worst. For chimneys older than 20 years or those showing visible signs of deterioration, twice-yearly inspections — once in spring and again in early fall — are a smart investment given our extreme climate.

Here's why Ottawa's winters make regular mortar inspection non-negotiable: our freeze-thaw cycle is relentless and brutal. Water penetrates mortar joints through microscopic cracks and pores in the masonry, then expands roughly 9 percent as it freezes below zero. Ottawa regularly dips 50 or more times per winter to -25 degrees Celsius or lower, and we receive over 200 centimetres of snow annually. Each freeze-thaw cycle widens existing cracks and creates new ones, progressively destroying the mortar that holds your chimney together from the inside out. A chimney with sound mortar joints in October can show significant spalling and joint deterioration by May — and the damage only accelerates in subsequent winters if it is not addressed.

What to look for during a mortar inspection: Visible gaps or recessed joints where mortar has washed away (mortar should be flush with or slightly recessed from the brick face, never deeply recessed), white powdery deposits or efflorescence on the chimney exterior (a sign that water is being drawn through the masonry), crumbling or missing mortar in horizontal bed joints (the most vulnerable spots in a chimney), cracked or broken brick faces around the mortar joints, and any signs of mortar that has been re-pointed with obviously different colour or texture (an indication of previous poor repairs). Pay special attention to the mortar joints below the roofline, where water runoff concentrates, and at the chimney crown where water meets mortar at the steepest angle.

A Level 1 WETT inspection or a visual inspection by a qualified chimney professional costs $250 to $450 in Ottawa and will document the condition of your mortar joints. If joints are recessed more than 1 to 1.5 inches deep or show active deterioration, tuckpointing (removal and re-pointing of damaged mortar) is typically required. Tuckpointing costs vary dramatically — $500 to $1,000 for isolated repairs on a few joints, or $1,500 to $2,500 for more extensive work across a significant section of the chimney. The key is catching deterioration early. A chimney that receives modest tuckpointing in year five of ownership will cost a fraction of what a full chimney rebuild costs in year ten.

Ottawa's ice storms compound the problem. Heavy ice accumulation on the chimney crown and at the roofline traps water and increases the freeze-thaw stress on mortar joints. The weight of ice can also shift masonry slightly, creating new cracks where none existed before.

Timing matters strategically in Ottawa. Spring inspections (late March through April) let you see what winter damage has occurred and schedule tuckpointing or crown repair before summer. Early fall inspections (September) catch any deterioration that may have developed over summer and allow repairs before the next winter assault begins. Attempting exterior mortar repair work in winter or during freeze-thaw conditions is pointless — mortar requires temperatures consistently above 5 degrees Celsius to cure properly, which is why professional masons typically work April through November in Ottawa.

If you have not had a chimney inspection in over a year, or if your chimney is 25 years old or older, schedule one now — the cost of an inspection is trivial compared to the cost of emergency chimney rebuilding after structural failure. You can browse experienced chimney technicians through the Ottawa Construction Network directory when you are ready to schedule that inspection or any necessary repairs.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Apple HVAC and mechanical
• The Egress Group Inc
• Renovo Construction
• McLaren Masonry
• Galico Home Comfort Inc.