Protect the opening at the top.
Choose a cap for the system
A cap is not one-size-fits-all. Flue dimensions, chimney construction and the connected appliance matter. Share photos taken safely from the ground and ask the provider to confirm the fit, material and mounting method before installation.
Separate the cap from the crown and flashing
The cap covers the flue opening. The crown is the top surface of a masonry chimney, and flashing is the roof-to-chimney junction. A new cap will not fix every leak. If you have water stains, request an assessment of the potential entry points.
Ask what the installation includes
Confirm removal of the old cap, any necessary preparation, secure fastening and the warranty terms. Tell the provider about nesting sounds or recurring draft issues. Do not climb onto the roof or disturb wildlife to inspect the opening yourself.