Establishment of flame spread rating. The surface flame spread rating of interior-finish material must not exceed the value shown in § 3280.203(b) when tested by Standard Test Method for Surface Burning Characteristics of Building Materials, ASTM E84-01, 2001, or Standard Method of Test of Surface Burning Characteristics of Building Materials NFPA 255, 1996, except that the surface flame spread rating of interior-finish materials required by § 3280.203(b)(5) and (6) may be determined by using the Standard Test Method for Surface Flammability of Materials Using a Radiant Heat Energy Source, ASTM E 162-94. However, the following materials need not be tested to establish their flame spread rating unless a lower rating is required by the standards in this part:

Flame-spread rating—76 to 200.

.035-inch or thicker high pressure laminated plastic panel countertop;

1/4-inch or thicker unfinished plywood with phenolic or urea glue;

Unfinished dimension lumber (1-inch or thicker nominal boards);

3/8-inch or thicker unfinished particleboard with phenolic or urea binder;

Natural gum-varnished or latex- or alkyd-painted:

1/4-inch or thicker plywood, or

3/8-inch or thicker particleboard, or

1-inch or thicker nominal board;

5/16-inch gypsum board with decorative wallpaper; and

1/4-inch or thicker unfinished hardboard,

Flame-spread rating-25 to 200,

Painted metal;

Mineral-base acoustic tile;

5/16-inch or thicker unfinished gypsum wallboard (both latex- or alkyd-painted); and

Ceramic tile.

Flame-spread rating requirements.

The interior finish of all walls, columns, and partitions shall not have a flame spread rating exceeding 200 except as otherwise specified herein.

Ceiling interior finish shall not have a flame spread rating exceeding 75.

Walls adjacent to or enclosing a furnace or water heater and ceilings above them shall have an interior finish with a flame spread rating not exceeding 25. Sealants and other trim materials 2 inches or less in width used to finish adjacent surfaces within these spaces are exempt from this provision provided that all joints are completely supported by framing members or by materials having a flame spread rating not exceeding 25.

Exposed interior finishes adjacent to the cooking range shall have a flame spread rating not exceeding 50, except that backsplashes not exceeding 6 inches in height are exempted. Adjacent surfaces are the exposed vertical surfaces between the range top height and the overhead cabinets and/or ceiling and within 6 horizontal inches of the cooking range. (Refer also to § 3280.204(a), Kitchen Cabinet Protection.) Sealants and other trim materials 2 inches or less in width used to finish adjacent surfaces are exempt from this provision provided that all joints are completely supported by a framing member.

Kitchen cabinet doors, countertops, backsplashes, exposed bottoms, and end panels shall have a flame spread rating not to exceed 200. Cabinet rails, stiles, mullions, and top strips are exempted.

Finish surfaces of plastic bathtubs, shower units, and tub or shower doors shall not exceed a flame spread rating of 200.

Fire protective requirements.

Materials used to surface the following areas shall be of limited combustible material (e.g., 5/16-inch gypsum board, etc.):

The exposed wall adjacent to the cooking range (see § 3280.203(b)(4));

Exposed bottoms and sides of kitchen cabinets as required by § 3280.204;

Interior walls and ceilings enclosing furnace and/or water heater spaces; and

Combustible doors which provide interior or exterior access to furnace and/or water heater spaces. The surface may be interrupted for louvers ventilating the enclosure. However, the louvers shall not be constructed of a material of greater combustibility than the door itself (e.g., plastic louvers on a wooden door).

No burner of a surface cooking unit shall be closer than 12 horizontal inches to a window or an exterior door with glazing.