What feature of a hearth extension is crucial for safety according to building codes?

A hearth extension plays a significant role in ensuring safety around fireplaces and stoves. One crucial feature that meets safety standards according to building codes is that it must be clearly marked. This marking assists in preventing accidents by designating the safe area around a heating appliance where individuals should avoid placing flammable materials. By having a well-defined and marked hearth extension, it helps occupants understand the boundaries to maintain an appropriate distance from the heat source, thus reducing the risk of fire hazards.

While anchoring, thickness, and insulation may also contribute to the functionality and durability of a hearth extension, the primary safety concern emphasized by building codes is clear marking. This aspect is vital for maintaining awareness of the hazardous zone, ensuring that users and visitors are informed and can navigate the space safely.