Toronto's climate is genuinely hard on masonry. The city experiences 70 to 90 freeze-thaw cycles per year — days when temperatures cross the 0°C threshold in either direction — and each cycle puts mechanical stress on every mortar joint in every exposed brick wall in the city. If your home has brick, and it was last repointed more than 15 years ago, spring is the right time for a close look at the mortar joints. Here are the five indicators that warrant a call to a masonry contractor.
1. You Can Scratch Mortar Out With a Key
Mortar that has retained its structural integrity resists casual abrasion. Mortar that has lost its binding strength — because the lime or Portland cement has carbonated past its useful life or because water infiltration has leached the calcium matrix — often degrades to a crumbly, almost sandy consistency. Run a key or a nail along several mortar joints at chest height and at grade level, where freeze-thaw exposure is most intense. If you can scrape material out easily, or if the joint crumbles rather than resisting the probe, the mortar has lost its structural contribution to the wall and repointing is overdue.
2. Joints Are Recessed More Than 5 mm Below the Brick Face
Intact mortar joints sit at or near flush with the brick face, forming a continuous water-resistant plane. As mortar erodes, the joint surface recedes — and the deeper that recession, the more surface area is exposed to water entry. A recession of more than 5 mm below the brick face creates a small channel that collects water and holds it against the brick, dramatically increasing freeze-thaw damage to the brick edges and to the deeper mortar remaining in the joint.
3. White Powder on the Brick Face (Efflorescence)
Efflorescence is the visible sign of water moving actively through masonry. Water entering through failed joints dissolves soluble salts — typically calcium carbonates and sulfates — from the mortar and brick material as it travels through the wall. When the water evaporates at the surface, it leaves those salts behind as a white, powdery, or crystalline deposit. Efflorescence itself doesn't damage brick, but it's a reliable indicator that water is travelling through the joint plane and that the mortar is no longer performing its moisture-management role.
4. Damp Interior Walls After Rain
If interior walls adjacent to exterior brick surfaces show damp patches, water staining, or — in more advanced cases — visible mould or mildew after heavy rain, water is entering through the masonry envelope. Failed mortar joints are one of the most common pathways. In Toronto's older housing stock, where cavity drainage details were often minimal or absent, water entering through the exterior joint face can track directly to interior finishes.
5. Spalling Brick Faces
Spalling — the progressive delamination and loss of the brick's surface layer — looks dramatic and is often the symptom that finally triggers a call. In many cases, spalling is a consequence of sustained water infiltration through adjacent failed mortar joints: water enters the joint, travels behind the brick face, freezes, and the expansion force pops the face off the brick body. By the time spalling is visible, the mortar joints have typically been failing for several seasons.
What to Do
If you observe any of these conditions, call a licensed masonry contractor for an assessment before the next winter season. Brick repointing is most effective and most economical when done before water infiltration has caused structural damage to the brick, lintels, or interior finishes.
Related services: Brick Repointing & Tuckpointing · Brick Repair & Restoration · Back to Elite Toronto Masonry
Written by the Elite Toronto Masonry Team