Final answer:
When constructing a floor in front of a fireplace with a span greater than 6 feet, a double joist or equivalent reinforcement is required to provide adequate support for the weight and heat of a wood stove or similar device.
Step-by-step explanation:
In front of a fireplace, when doing floor construction, you should use a double joist or stronger structural support if the header spans more than 6'.
This is to ensure adequate support and safety, especially considering that a wood stove or other efficient heat device will be used, which implies significant weight and heat consideration. It is important to take into account the stress and load that will be applied to the floor section in front of the fireplace to prevent any structural failures.
When constructing a floor in front of a fireplace, especially if the header (a horizontal beam supporting the structure above) spans more than 6 feet, it's common to use a "fireplace foundation support" or "fireplace foundation shelf."
This support structure is designed to carry the load of the floor joists and maintain the necessary clearance and safety around the fireplace.