What a Hunterdon County winter does to a chimney
A chimney in Clinton Township absorbs punishment that has nothing to do with how many fires you light. The masonry stands exposed to the full swing of a Hunterdon County year, the damp heat of a rural summer, the soaking rains that move through the Raritan valley, and then the relentless freeze and thaw of a hill-country winter where the temperature crosses the freezing line again and again between dusk and dawn. Brick and mortar are porous by nature, so they soak up water during every wet spell, and the moment that trapped water freezes it swells and works the masonry apart from within. Each overnight freeze widens the cracks a fraction more, and the crown at the very top, the most weather-beaten surface on the whole stack, is almost always the first piece to surrender.
Heavy wood heat layers on a second and entirely different strain. Every fire deposits creosote on the inner walls of the flue, a sticky, flammable film that builds up in coats and slowly squeezes the channel the smoke has to climb. A flue partly sheathed in hardened creosote is at once a fire hazard and a draft problem, since the same coating that can ignite also strangles the airflow the fire depends on. The two forces gnaw at opposite ends of the chimney at the same moment, water and ice prying at the structure from the cap down while creosote piles up in the flue from the firebox up, which is precisely why a hard-working chimney out here needs eyes on it on a schedule, not only after something has plainly gone wrong.