All Articles

How Freeze-Thaw Cycles Damage Masonry in Northern Ontario

Northern Ontario winters are hard on masonry. Water enters small cracks, freezes, expands, and widens those cracks over time. Understanding this process helps explain why masonry maintenance matters.

Greater Sudbury regularly sees dozens of freeze-thaw cycles every winter — days where temperatures climb above zero and then drop back below freezing overnight. For masonry, this is one of the most damaging forces it faces.

The process works like this: water — from rain, snowmelt, or condensation — finds its way into small cracks or porous areas in brick, mortar, or stone. When that water freezes, it expands by roughly nine percent. That expansion exerts enormous pressure on the surrounding material, widening the crack slightly. When it thaws, the crack is a little bigger than before. Repeat this dozens of times over a single winter and the damage compounds quickly.

Mortar joints are the most vulnerable point. Mortar is more porous than brick and absorbs water readily. Once mortar starts to erode, water has a direct path into the wall cavity or chimney core, where freeze-thaw damage can occur out of sight.

Brick itself can also be affected, particularly older soft brick. Spalling — where the face of the brick flakes away — is a direct result of freeze-thaw action inside the brick. Once the face is gone, the brick absorbs water even more readily and the deterioration accelerates.

The best defence is keeping mortar joints in good condition and ensuring water cannot pool against masonry surfaces. Proper flashing, grading, and drainage all play a role. Chimney caps and crowns prevent water from entering the flue directly.

If you have noticed cracks, crumbling mortar, or spalling brick after this past winter, it is a good time to have the masonry inspected before the next freeze season. Early repairs are always less expensive than waiting. Reach out to A1 Creative Masonry for a site assessment in Greater Sudbury and surrounding areas.

A1 Creative Masonry — Greater Sudbury

Have a masonry question or need a site visit?

We serve Greater Sudbury and surrounding areas. Get in touch for an assessment — we respond promptly.

Request a Site Visit