Water is a chimneys worst enemy. Chimney leaks, fireplace leaks, and water damage may be from exterior water intrusion caused by no chimney cap, crown cap & deterioration, mortar joint, deterioration, cracking in the masonry construction, flashing & roof leaks, shoulder slab gaps, foundation cracking, and/or flue gas condensation (over or under sized chimney liners).
Chimney rebuilds include set up (scaffolding in most cases), tear down & disposal, and code reconstruction of your existing chimney. These classifications are the most common of required chimney rebuilds:
Partial chimney rebuilds: small chimneys (no scaffolding) or only the top few courses of a large chimney (+ new crown).
Roof line up chimney rebuilds: Substantial mortar and/or brick deterioration has eliminated the possibility of pointing restoration. The structure is torn down to the flashing area near the roofline, and then the chimney rebuild commences (+ new crown).
Total chimney rebuilds: Complete tear down of the outer layer of the brick on a chimney (+ new crown). In most cases the firebox, hearth, and smoke chamber do not have to be removed (minor brick chimney repair is usually sufficient). Total chimney rebuilds are necessary when the chimney is leaning, has severe mortar deterioration or severe brick cracking has occurred from ground level up, etc.