Final answer:
The minimum thickness required for the footings of masonry fireplaces and chimneys should be constructed according to building codes, which might commonly be around 12 inches; however, it's important to verify this with local regulations.
Step-by-step explanation:
The question asks about the minimum thickness required for the footings of masonry fireplaces and their chimneys. Footings are crucial in construction as they are the supporting base of the structure. According to building codes, the footings for masonry fireplaces and their chimneys should be constructed of concrete or solid masonry with a minimum thickness.
Though the exact thickness requirement isn't provided in the question, typically, codes may specify a minimum thickness such as 12 inches, depending on the structure's size and the load it will bear. It's important to consult the latest building codes or a professional engineer for the specific requirements in your area.
Making sure fireplaces and their chimneys have the proper footing thickness ensures not only stability but also safety, especially considering that efficient devices like a wood stove may be used to prevent heat from escaping through the chimney.