803.15.2 Set-Out Construction
Where walls and ceilings are required to be of fire-resistance-rated or noncombustible construction and walls are set out or ceilings are dropped distances greater than specified in Section 803.15.1, Class A finish materials, in accordance with Section 803.1.1 or 803.1.2, shall be used.
- Where interior finish materials are protected on both sides by an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2.
- Where interior finish materials are attached to noncombustible backing or furring strips installed as specified in Section 803.15.1.1.
- Where the combustible void is filled with a noncombustible material.
The hangers and assembly members of such dropped ceilings that are below the horizontal fire-resistance-rated floor or roof assemblies shall be of noncombustible materials. The construction of each set-out wall and horizontal fire-resistance-rated floor or roof assembly shall be of fire-resistance-rated construction as required elsewhere in this code.
Exception: In Type III and V construction, fire-retardant-treated wood shall be permitted for use as hangers and assembly members of dropped ceilings.