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Spalling: when brick faces give up

Spalling is brick shedding its face: flakes, sheets, or chunks popping off and often piling up in the gutter or flowerbed below. It is the signature failure of wet-climate masonry, and around the Sound it follows a specific script: brick absorbs water for months, a cold snap freezes the trapped moisture, expansion shears the face off, and the newly exposed soft interior absorbs water even faster. Spalling accelerates, by design of the physics.

Where it starts tells you why

Spalling concentrated in the top courses points at a failed crown raining water down into the stack. Spalling on one weather face points at wind-driven saturation of unsealed brick. Random single spalls on an otherwise sound chimney are often just the era's occasional soft brick meeting its sixtieth winter. The pattern is the diagnosis.

The repair sequence

Fix the water source first, crown, cap, flashing, or joints. Replace the spalled units with matched brick, because a spalled face never heals and sealing over it traps moisture in the exposed soft clay, accelerating exactly what you are trying to stop. Then, with the masonry sound and dry, a breathable repellent slows the next cycle of absorption on the weather faces.

Common questions