In NFPA 220, the designation 2HH, the H stands for what?

In NFPA 220, the designation 2HH, the H stands for what?

• A. Heavy timber
• B. Hollow
• C. Horizontal
• D. High

Answer: (A)

NFPA 220 uses letter codes to describe the material and form of the building’s structural framing. In the designation 2HH, the H stands for heavy timber, signaling that the primary structural members are large-dimension timber. Heavy timber burns at a slow, predictable rate and maintains strength longer in a fire, which is why this material is specifically called out in the standard. The double H simply reinforces that this heavy timber characteristic applies to the parts of the structure defined by the designation. Hollow, horizontal, or high don’t correspond to NFPA 220’s material designation scheme.

NFPA 220 uses letter codes to describe the material and form of the building’s structural framing. In the designation 2HH, the H stands for heavy timber, signaling that the primary structural members are large-dimension timber. Heavy timber burns at a slow, predictable rate and maintains strength longer in a fire, which is why this material is specifically called out in the standard. The double H simply reinforces that this heavy timber characteristic applies to the parts of the structure defined by the designation. Hollow, horizontal, or high don’t correspond to NFPA 220’s material designation scheme.