What the shore climate does to a Red Bank chimney
The Jersey shore is rough on a chimney in a way an inland town never quite matches. The heating months run long and damp, and a home near the Navesink leans on its fireplace or stove through a season of raw, wet cold, so a flue that would see light duty elsewhere burns steadily from the first hard frost into spring. Any fire that burns cool, and an older riverfront flue often drafts a touch sluggishly in damp air, lays down creosote on the inside of the liner. That tarry film is the gravest hazard a chimney carries, because it is fuel sitting in the exhaust passage, and once it cakes on thick enough a stray ember or an overfired stove can light it into a flue fire. Long, damp coastal winters are exactly why a yearly sweep here is not something to put off.
Then there is the water, and on the coast it comes from every direction. Salt rides in on the air off the river and the bay and works into mortar and porous concrete in a way plain rainwater does not, and the chimney is the most exposed masonry on the whole house, standing up above the roofline with nothing to shield it. Wind-driven rain and snowmelt soak the brick, the joints, and the crown, then the temperature drops and that trapped moisture freezes and swells. Run that freeze-and-thaw cycle through a shore winter and it spalls the face off brick, splits the crown, and opens the joints, and every fresh crack drinks in more salt water for the next freeze. The leak that surfaces in a Red Bank ceiling in March was very often a hairline split in the crown the autumn before, and catching it then is the difference between a small repointing and a full rebuild.