The minimum required extension for chimney footing is aimed at:

The minimum required extension for chimney footing is aimed at preventing structural failure. This extension is crucial because it ensures that the footing provides adequate support for the chimney, which is a vertical structure that can be subject to various forces, including wind loads and the weight of the chimney itself. If the footing is not extended sufficiently, it may not distribute the weight of the chimney adequately, leading to settling, cracking, or even collapse over time.

A properly extended chimney footing helps maintain the integrity of the chimney and connects properly to the foundation, ensuring that it can withstand environmental stresses without compromising stability. While ensuring proper ventilation, facilitating drainage, and enhancing aesthetic appeal are important considerations in chimney design and construction, the primary focus of the chimney footing extension is to prevent structural failure and ensure the safety and longevity of the chimney.