Brick spalling occurs when moisture enters the stone causing it to deteriorate and break apart, or spall. Causes of brick spalling include weather, dripping water or faulty mortar.
In cold, wet climates, the porous surface of a brick absorbs water, and the brick expands and cracks when freezing occurs. Water may also be introduced into a brick's surface from leaking windows, doors, chimneys, gutters or from holes in the mortar caused by hot, wet, cold or dry surroundings. Spalling is common in basements and around foundations. A masonry sealant protects a brick's surface, but allows it to breathe. Providing good drainage around foundations helps prevent spalling. Before replacing damaged bricks, first identify and correct the cause of the moisture.