The cap: over the flue opening
A chimney cap is a component over a flue opening. When replacement is proposed, ask for the existing and proposed component to be identified. Measurements and the installed system matter; a visual resemblance is not enough to select a part.
The crown: the masonry chimney's top surface
The crown forms the top surface around the flue on a masonry chimney. It is separate from the cap. A recommendation for crown repair should make clear which surface is affected and how the work relates to the surrounding flue and masonry.
The chase cover: a different assembly
A framed chimney enclosure, or chase, can have a top cover. That cover is a different component from a masonry crown. Begin by identifying the type of system rather than using every chimney-top term interchangeably.
Four questions for a clear proposal
Which component is being repaired or replaced? What finding supports that recommendation? What surrounding connections are included? What remains outside the scope?
A marked photograph and a plain-language explanation can help answer those questions. Keep the component name and its location together in your notes so that a discussion about one part is not confused with a promise about the complete chimney.
The goal is a clear decision about the proposed work. This guide does not establish what component is suitable for a particular appliance or chimney; that selection needs to be made for the actual system.
Further reading
Independent educational resources. A source link does not imply certification, affiliation, or endorsement.