Final answer:
For a fireplace with a 6 square foot opening and a 24-inch firebox depth, the minimum hearth extension on the side traditionally was 5 inches, but newer guidelines suggest it should be at least 8 inches. Current building codes should be consulted for exact requirements.
Step-by-step explanation:
The question is asking to determine the minimum hearth extension on the side of a fireplace that has a 6 square foot opening and a firebox depth of 24 inches.
Referring to safety standards and previous rules of thumb, the side extension of the hearth traditionally was approximately 5 inches side-to-side.
\However, more recent recommendations suggest up to 8 diameters side-to-side for the hearth extension, depending on the fireplace design and the efficiency of devices used, such as a wood stove, to prevent heat loss through the chimney.
In this case, without a direct standard provided, using the older rule of thumb would mean a minimum side extension of 5 inches, but it may be considered more prudent to adopt the newer guidance, which would imply at least 8 inches side-to-side for the hearth extension. Since the question does not specify which rule to use, the best course of action would be to consult current local building codes or standards for the exact measurement required.