Limited-Combustible (Material) refers to a building construction material not complying with the definition of noncombustible that, in the form used, has a potential heat value not exceeding 3500 Btu/lb, tested per NFPA 259, and includes either of the following: (1) materials having a structural base of noncombustible material, with a surfacing not exceeding 1/8 in (3.2 mm) that has a flame spread index not greater than 50; or (2) materials, in the form and thickness used, having neither a flame spread index greater than 25 nor evidence of continued progressive combustion.

• A. A material that is noncombustible.
• B. A material with no flame spread and no heat release.
• C. Refers to a building construction material not complying with noncombustible that, in the form used, has a potential heat value not exceeding 3500 Btu/lb, where tested in accordance with NFPA 259, and includes either of the following: (1) materials having a structural base of noncombustible material, with a surfacing not exceeding 1/8 in (3.2 mm) that has a flame spread index not greater than 50; or (2) materials, in the form and thickness used, having neither a flame spread index greater than 25 nor evidence of continued progressive combustion, and of such composition that surfaces that would be exposed by cutting through the material on any plane would have neither aflame spread index greater than 25 nor evidence of continued progressive combustion.
• D. A material that will burn with high heat.

Answer: (C)

Limited-Combustible materials are those that don’t meet the full noncombustible standard but are restricted in how they burn by specific tests. The definition relies on a maximum heat value of 3500 Btu per pound, determined under NFPA 259, and two ways the material can qualify.

One route is a product with a structural base of noncombustible material, plus a surfacing layer no thicker than 1/8 inch that has a flame spread index no greater than 50. The alternative route is the form and thickness used, where the material shows a flame spread index no greater than 25 and no evidence of continued progressive combustion. An important assurance is that any surfaces exposed if you cut through the material would also have a flame spread index not exceeding 25 and no continued progressive combustion.

This matches the option that explicitly states those exact criteria, including the 3500 Btu/lb heat value, NFPA 259 testing, and the two specified configurations. The idea is that the material isn’t fully noncombustible, but its combustibility is limited to these defined, controlled limits.

The other choices don’t fit because:

• One describes a fully noncombustible material, which is not what limited-combustible means.

• Another claims no flame spread and no heat release at all, which is stricter than the defined limits.

• The last states it will burn with high heat, which contradicts the limited-combustible criteria.