If a chimney has a dimension parallel to the ridgeline greater than 30 inches, what must be provided?

When a chimney has a dimension parallel to the ridgeline greater than 30 inches, it is necessary to provide a cricket. A cricket is a small roof structure that is installed on the uphill side of a chimney to divert water and prevent it from pooling around the chimney base. This is crucial because, without a cricket, water can accumulate at the base of the chimney, leading to leaks or water damage within the structure over time.

The requirement for a cricket is based on principles of effective roof drainage and preventing moisture issues. Chimneys that extend beyond typical dimensions can create unique challenges regarding water flow and collection, making the inclusion of a cricket essential for proper roof performance and longevity.

The other options do not address the specific needs regarding drainage and water management in this scenario. A flue is primarily concerned with directing smoke and gases, a hood serves to redirect exhaust in ventilation systems, and a cap is meant to protect the flue opening from debris and animals. None of these options fulfill the functional need for water management around a chimney that exceeds the specified dimension.