To which type of dwellings does the maximum flame spread index and smoke developed index not apply?

The maximum flame spread index and smoke developed index are crucial aspects of fire safety regulations that dictate how materials used in construction should behave when exposed to fire. These indices are particularly relevant in larger, more complex structures where the potential for fire spread can pose significant risks to many occupants and require stringent safety measures.

In the case of one and two family dwellings, which typically include single-family homes and duplexes, these buildings are often subject to different fire safety standards. Generally, the construction materials and designs used in these smaller dwellings are less complex than those found in high-rise buildings or hospital facilities. Therefore, the same level of regulation regarding flame spread and smoke development is not applied, reflecting the lower density and occupancy risks associated with these residential types.

The rationale behind this distinction is that one and two family dwellings typically have fewer occupants and less overall risk of catastrophic fire events compared to larger facilities. Consequently, regulatory standards might allow for more flexibility in the choice of materials permitted for construction in these residential buildings.