Final answer:
The front hearth of a fireplace opening less than 6 sq. ft. should traditionally extend at least 16 inches in front and 8 inches on both sides, although newer guidelines may suggest larger dimensions for enhanced safety and heat efficiency.
Step-by-step explanation:
When considering the dimensions of a hearth for a fireplace opening that is less than 6 sq. ft., it is important to follow safety guidelines to prevent fire hazards. An older "rule of thumb" suggested that the front hearth should extend at least 16 inches deep in front of the fireplace opening and at least 8 inches wide on both sides.
However, more recent recommendations may advise a greater depth and width to ensure adequate protection and heat absorption, such as a ratio of diameters side-to-side and deep, potentially leading to dimensions as large as 15 diameters deep, particularly when assuming a wood stove or other efficient device is being used to prevent most heat from just escaping through the chimney.
The front hearth of a fireplace opening less than 6 sq. ft. should traditionally extend at least 16 inches in front and 8 inches on both sides, although newer guidelines may suggest larger dimensions for enhanced safety and heat efficiency.