Which component is required for a masonry chimney?

A crown cap is a required component for a masonry chimney as it serves a crucial function in protecting the chimney structure and ensuring safe operation. The crown cap is positioned at the top of the chimney and is designed to direct rainwater away from the flue and prevent moisture from seeping into the chimney, which can lead to deterioration of the masonry over time. It also helps to minimize the chances of debris entering the chimney, which can pose fire hazards.

While the other components like spark arrestors and rain caps are important for different reasons—such as preventing sparks from escaping and keeping rain out—they are not strictly required for the basic structural integrity of the chimney itself. The crown cap is essential for maintaining the operational safety and longevity of the masonry chimney.