What a southwest Ohio winter does to a chimney
The chimney is the most exposed masonry on the house. It stands above the roofline with weather hitting it from every direction, and in the Miami Valley that weather swings hard. A January here can run from a wet thaw into a hard overnight freeze and back again within a single week, and that cycle is what quietly takes a chimney apart. Rain and snowmelt soak into the brick and the mortar joints, the temperature drops, the trapped water freezes and expands, and every freeze pries the joint open a hair wider than it was. Repeat that across a few dozen cycles a winter, season after season, and a chimney that looked solid starts shedding mortar, spalling brick faces, and letting water reach places it was never meant to go.
Water is the slow enemy, but creosote is the fast one. Burning wood in a Middletown fireplace through a long heating season coats the inside of the flue with creosote, a tar-like residue that builds up a little with every fire. It is also flammable. Let it accumulate and a single hot, fast-burning fire can ignite the deposit inside the flue, and a chimney fire is exactly the emergency a regular sweep is meant to prevent. Older flues that are oversized for a modern insert, or chimneys that run cold on the exterior wall of a frame house, build creosote faster because the smoke cools and condenses before it ever clears the top. Knowing which local homes burn dirty is part of what we bring to the job.