How far should the footing for a masonry chimney extend beyond the face of the fireplace or foundation wall?

The correct answer indicates that the footing for a masonry chimney should extend 6 inches beyond the face of the fireplace or foundation wall. This extension is crucial for providing adequate support and stability for the chimney structure. When a chimney is built, it experiences significant vertical and lateral loads due to its height and weight. Ensuring that the footing extends properly helps to distribute these loads effectively to the soil below.

An extension of 6 inches helps to prevent settling or shifting of the chimney which could lead to structural failures or safety hazards, such as cracks or even total collapse. It also provides a buffer against potential erosion or any water that may collect near the chimney base, which could otherwise undermine the footing.

Other options reflect extensions that are either insufficient or excessive for typical building practices concerning chimney stability, leading to potential issues that could arise over time. Thus, a 6-inch extension has been determined to be the standard for effective chimney footing design.