What a North Texas year actually does to a chimney
The thing that wears on an Arlington chimney is rarely the fire inside it, because that fire burns so seldom. It is the weather working on the masonry outside, and North Texas weather is harder on a chimney than its mild reputation suggests. Summers here are long and brutally hot, and the relentless sun bakes the concrete crown until it develops the surface cracks that let the first rains run straight into the structure. Then the spring storm season arrives with wind-driven rain and the hail this part of Tarrant County is known for, and that hail batters crowns, dents caps, and chips the mortar at the top of the stack. The masonry that looked fine last fall can be visibly opened up by the time the next cold front rolls through.
Underneath all of that sits a problem peculiar to this region, the expansive clay soil the whole metroplex is built on. That clay swells when the rains come and shrinks hard during the summer droughts, and the ground heaves and settles with it season after season. A masonry chimney is a heavy, rigid column anchored in that moving soil, and over years the movement tilts stacks, opens cracks where the chimney meets the house, and separates the flue tiles inside. A lot of the leaning chimneys and the gaps between chimney and roofline we are called out to in Arlington trace straight back to that soil rather than to anything the homeowner ever did. Reading a chimney here means reading what the climate and the ground have been doing to it, not just sweeping out the soot.