Manteno chimney with flaking brick faces: freeze-thaw spalling and how we replaced the damaged courses

By Jacob Dove, Friendship Chimney Sweep

What the homeowner found

The house is a 1950s brick ranch a few blocks from the older part of Manteno, the kind of solid, modest home that went up as the village grew in the postwar years. The owner called after a spring cleanup turned up a small pile of brick chips and fine red grit in the bed along the side of the house. From the yard, the upper third of the chimney looked rough and pitted, with several bricks missing their smooth outer face entirely.

That condition is called spalling. Brick is porous. When water soaks into it and then freezes, the ice expands and pushes the outer face off. Northern Illinois gives masonry dozens of freeze-thaw cycles in a typical winter, and a chimney standing above the roofline takes the worst of the wind-driven rain and snow. On this stack we counted more than twenty bricks with face loss, nearly all of them in the top six courses [Observed].

Why the damage was concentrated at the top

The pattern pointed straight at the crown, the concrete cap that sheds water off the top of the chimney. This one was a thin mortar wash, troweled flat and flush with the brick, with no overhang and no drip edge. It had cracked through in two places. Water ran into those cracks, soaked down into the top courses from inside, and ran off the flush edge straight down the brick face instead of dripping clear of it. The bricks lower on the stack, which dried out faster, were mostly sound.

We also found that someone had sprayed a clear coating on the chimney years earlier. A film-forming sealer can trap moisture behind the brick face and make spalling worse, which is why we use only vapor-permeable water repellents, and only after the source of the water is fixed. Our Level 2 camera check of the flue showed the clay tiles were intact, so the damage was limited to the outside masonry.

How we repaired it

We cut out every spalled brick and replaced it with salvage-matched brick of the same size and a close color, set in a mortar softer than the brick so any future stress shows up in the joint, not the brick. We repointed the loose joints around the repairs. Then we removed the failed wash and formed a new crown with a proper slope, a drip edge that sets water clear of the face, and a bond break around the flue tile so the two can move independently. A stainless cap went on top to keep rain out of the flue itself.

Jacob Dove, who founded the company and has 29 years in the trade, walks owners through photos of every course we replace. We work to the NFPA 211 standard and are Insured & Bonded. Masonry repair pricing is published on the pricing page, and you can reach us seven days a week, 7am to 9pm, at (815) 449-4264. Please do not climb a roof to check a chimney yourself; binoculars from the ground and a look at what lands in the flower beds will tell you when it is time to call.

If this sounds like your house: we handle chimney repair across Kankakee County, and our Manteno page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.

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