Masonry chimney flues must have a cleanout opening with a minimum height of what dimension?

The correct dimension for a cleanout opening in masonry chimney flues is 6 inches. This specification ensures that the cleanout is adequately sized for maintenance and cleaning purposes, allowing for the effective removal of soot, creosote, and other debris that can accumulate within the flue. Having a cleanout of this size facilitates regular inspection and ensures that the chimney remains safe and functional.

Additionally, standards and codes often dictate this minimum height to balance practical cleaning needs with structural considerations. A cleanout opening that is too small may hinder proper access and make chimney maintenance more difficult, potentially leading to safety issues. Maintaining the right dimensions helps ensure compliance with safety codes and promotes the longevity of the chimney system.