The crown is the top masonry water-shedding surface, not the metal cap over a flue. A repair needs to account for shape, movement and material condition.
Published by Chimney Sweep Pages · September 24, 2026 · Editorial method
First decision
Arrange assessment; avoid roof access and keep clear of loose overhead material.
Possible explanations—not a diagnosis
Water exposure and material deterioration
Poor water-shedding shape or failed joints
Movement between the crown and flue components
Several conditions can occur together. Only an appropriate on-site assessment can distinguish them in your home.
What the investigation should clarify
A contractor should distinguish a surface defect suitable for a specified repair from deterioration requiring replacement. Ask how the proposed crown will manage runoff and movement. The scope should identify preparation, material and warranty exclusions.
A coating described as waterproof is not evidence that an unsound crown has been rebuilt.
One question worth asking
Can you show which parts remain sound and explain why the proposed repair is sufficient?
Ask for the findings, access limitations and proposed next steps in writing. Keep diagnosis separate from a repair estimate so you can seek another opinion with the same evidence.