Water coming in around a chimney

Very commonly, yes. Step flashing, counter flashing, the absence of a cricket, masonry condition, crown and cap, and mortar joints can all admit water while the surrounding roofing is entirely sound.

As a standalone fix, no. Sealant has a limited service life and a joint depending on it alone will leak again. It has a role supporting a properly built flashing detail or as an explicitly temporary measure, but it should be described that way.

It is a small peaked structure built on the upslope side of a chimney to divert water and snow around it rather than letting them pile against the face. Wider chimneys on a slope generally need one, and its absence is a recurring cause of leaks and rot at that face.

A frequent cause is step flashing that was reused rather than replaced, or counter flashing that was surface-sealed instead of engaged with the masonry. Ask specifically what was done at the chimney; it is a common place for a replacement to cut a corner.

Usually a mason, unless the roofing company's written scope expressly includes masonry. Crown, cap, mortar and brick work are a different trade, and the proposal should state clearly what is excluded.

Capping an unused flue is common and can stop water entering the chase, but it does not fix flashing at the roof line and it can create condensation issues if the chase is not handled properly. Treat it as one part of a plan rather than the whole answer.

Alongside a general roof inspection is reasonable for a chimney with no known problem; more often if there is any history of leaks there. Flashing and sealant age even when nothing is visibly wrong, so periodic checking catches a failing detail before it leaks.

A chimney cap keeps out rain, snow, and animals and protects the crown and flue liner from water entry, which is a different function from the roof-line flashing. Its absence is a separate issue from the chimney leak this page describes, but it is worth checking at the same time.

Yes. Ice and snow piling against the upslope side of a chimney without a cricket can back water up under the flashing during a thaw, producing staining that looks identical to a flashing failure. Both point toward the same fix: a properly built cricket and integrated flashing.

No — a leaning or tilted chimney is a structural or masonry concern, not a roofing one, and should be assessed by a mason or structural professional. The roofing scope at a chimney is limited to the flashing and cricket, not the masonry's stability.

It can, since it eliminates the penetration and its flashing details altogether, but full removal is a larger structural and roofing project than capping or reflashing. Weigh it against simply correcting the flashing if the chimney is otherwise sound and not a nuisance.

Yes. Water tracking down the chimney chase can wet insulation and framing inside the chase without necessarily reaching a visible interior surface right away, which is part of why a musty smell near an unused fireplace is worth investigating even without staining.