46 CFR § 116.422 - Ceilings, linings, trim, interior finish and decorations.
(a) Ceilings, linings, and any furring incidental to their installation in control spaces, passageways, stairways, accommodation spaces and service spaces must be of noncombustible material in accordance with § 164.009 in subchapter Q of this chapter, or other standard specified by the Commandant.
(b) Bulkheads, linings and ceilings may be covered by a combustible interior finish provided that such a finish is:
(1) Approved under § 164.012 in subchapter Q of this chapter, or other standard specified by the Commandant; or
(2) Listed by Underwriters Laboratories, does not exceed 2 millimeters (.075 inches) in thickness, and has a flame spread rating of not more than 20 and a smoke developed rating of not more than 10 when tested in accordance with ASTM E 84 (incorporated by reference, see § 114.600) or UL 723 by an independent laboratory.
(c) Bulkheads, linings, and ceilings in high risk accommodation spaces may have a combustible veneer trim and decorations that do not meet the requirements of paragraph (b) of this section, provided:
(1) The overall thickness of the combustible veneer does not exceed 2 millimeters (.075 inches); and
(2) The total volume of the combustible face trim, moldings, and decorations, including veneers, in any space does not exceed a volume equivalent to a 2.5 millimeter (0.1 inch) veneer on the combined area of the bulkheads and ceiling of the space.
(d) Combustible veneers may not be used in passageways, stairway enclosures or in low risk accommodation spaces. Combustible veneers, trim and decorations may not be used in or extend into hidden spaces such as behind linings or ceilings.
(e) Partial bulkheads or decks used to subdivide a space for artistic treatment and privacy must meet the requirements of Class C bulkheads.
(f) Nothing in this subpart may be construed as prohibiting the covering of any surface, including the surfaces of corridors, stairway enclosures, and hidden spaces, with a reasonable number of coats of paint or with a marine finish meeting the requirements of § 164.012 in subchapter Q of this chapter or other standard specified by the Commandant.