What is spalling in masonry?
Spalling is the flaking, chipping, or breaking away of masonry units or surface material caused by moisture infiltration and repeated freeze-thaw cycles that create internal pressure.
When water enters brick, stone, or concrete and then freezes, it expands and exerts pressure on the masonry material. As this ice thaws and refreezes repeatedly over winter months, small pieces of the surface begin to flake or chip away. This process is called spalling. Unlike surface staining or discoloration, spalling is structural damage that physically removes material from the masonry face.
Spalling often appears as irregular chunks or layers of brick or stone breaking free, leaving rough or pitted areas behind. It typically starts at corners, edges, joints, or areas where water collects most easily. Once the outer layer spalls, interior layers become exposed and vulnerable to more rapid deterioration.
The damage matters because it signals water is moving into the masonry assembly. Left unaddressed, water can travel deeper into walls, damaging the mortar, the brick backing, and potentially the structure behind. In Connecticut's climate with regular freeze-thaw cycles, spalling is a common problem on older homes and buildings. Masonry contractors can assess whether spalling is limited to surface scaling or indicates deeper moisture issues requiring tuck-pointing, sealing, or other repairs.