Exterior brick spalling and crumbling — Barcelona, Catalonia

Spalling is when the face of a brick flakes, chips, or pops off, exposing the softer interior to further damage. The primary cause is the freeze-thaw cycle: moisture penetrates the brick, freezes, expands, and breaks off the outer layer. Contributing factors include poor-quality or too-soft brick, deteriorated mortar joints that let water in, moisture trapped behind the brick by impermeable coatings or missing weep holes, and efflorescence (white salt deposits) that signals chronic moisture movement. Left unaddressed, spalling spreads from cosmetic surface damage to structural compromise — crumbling bricks weaken the wall section and can allow water into the wall cavity. Repair involves repointing (removing old mortar and pressing in new mortar matched to the original), replacing individual severely damaged bricks, and addressing the moisture source. A mason evaluates whether the damage is cosmetic (surface repoint) or structural (partial wall rebuild), checks flashing and weep holes, and selects mortar that matches the original in strength and composition — using too-hard mortar on old soft brick accelerates damage.