People assume masonry problems belong to northern winters, and DFW’s mild reputation lulls them. The truth is meaner: our climate is nearly optimized to disassemble masonry, not through severity, but through variety and cycling. Four weapons, in seasonal order:
Winter: the freeze-thaw wedge
Minneapolis freezes in November and stays frozen, one cycle. Dallas crosses 32°F thirty-plus times a winter, warm rain loading the masonry, then a snap freeze pressing the 9%-expansion wedge, then thaw, then again. Cycle count is what kills brick, and we lead the league. Result: spalling, widening crown cracks, and mortar joints crumbling from the inside.
Summer: heat and UV
Forty consecutive 100°F days do quieter work: masonry expands and contracts through daily 40-degree swings, working every joint like a hinge; UV cooks flashing sealants and water-repellent coatings toward brittleness; and mortar’s slow chemical aging accelerates with temperature. Summer doesn’t break the chimney, it removes the margins winter will exploit.
Spring: the hail lottery
DFW sits in one of the continent’s most active hail corridors. The chimney is the roof’s highest, most exposed structure: crowns take direct strikes, caps dent and displace, and counter-flashing edges bend. Hail damage is also the most-claimed chimney event in the region, document fast when it happens.
Year-round, underground: the clay
Expansive clay swells wet and shrinks dry, and the chimney, the heaviest, most rigid element on the house, telegraphs every move: stair-step cracks, separation gaps, tile shear inside the flue. It’s the one weapon that attacks from below, the movement guide covers its signature.