Fireplaces must have their hearths made with a minimum thickness of how many inches?

In commercial building codes, the specifications for fireplace hearths are designed to ensure safety and functionality. A minimum hearth thickness of 4 inches is established to provide adequate protection against heat transfer and to prevent the potential for fire hazards. The hearth acts as a barrier that absorbs and dissipates heat, helping to prevent it from affecting surrounding materials or causing ignition.

Thicker hearths, such as those measuring 6 or 8 inches, would likely provide even more protection but are not required by standard codes. In contrast, a hearth thickness of 2 inches would not meet safety standards due to insufficient heat resistance, which could lead to unsafe conditions. The choice of 4 inches is a balance between safety, structural necessity, and code requirements, ensuring that the fireplace performs effectively without compromising safety.